I saw this on another site:
“Classical Theravāda” excludes that other now dead Theravāda, the Abhayagiri Vihāra. They also studied Mahāyāna, but in what sense are they less than the one we know today?
Here is the Mahavamsa history of this group
ch33
A then known by the name Mahatissa, who had frequented the families of laymen, was expelled by the brotherhood from our monastery for this fault, the frequenting of lay-families. His disciple, the them who was known as Bahalamassutissa, went in anger to the Abhayagiri (vihãra) and abode there, forming a (separate) faction. And thenceforward these bhikkhus came no more to the Mahavihara: thus did the bhikkhus of the Abhayagiri (viliüra) secede from the Theravada. From the monks of the Abhayagiri -vihara those of the Dakkhina-vihara separated (afterwards); in this wise those bhikkhus (who had seceded) from the adherents of the Theravada were divided into two (groups).He (the king) built the cells of the vihara so that a greater number were joined together, for he reflected: ‘In this way it will be possible to restore them.’
ch 36After the death of BHATIKA TISSA (his younger brother) KANITTHA TISSA reigned eighteen years in the island of Lankä. Since he was well pleased with the thera Mahanaga in the Bhutarama he built for him in splendid fashion the Ratanapasada in the Abhayagiri. Moreover, he built in the Abhayagiri a wall and a great parivena and a great parivena besides in the (vihara) called Manisoma. In that place he built a temple for the cetiya and in like manner for the Ambatthala-thupa; and (he ordered) the restoration of the temple in Nagadipa. Doing away with the boundary of the Mahavihara, the king built there the row of cells (called) Kukkutagiri with all things provided. In the Mahävihãra the ruler of men built twelve great four-sided pasadas, admirable to see and beautiful, aria he added a mantling to the thupa of the Dakkhinavihara, and a refectory besides, doing away with the boundary of the Mahameghavana. And moving the wall of the Mahavihära to the side, he also made a road leading to the Dakkhinavihara. He built the Bhutaramavihara and the Ramagonaka, and the arama of Nandatissa besides.
In like manner he appointed then a great Vesakha-festival, and yearly did he distribute the six garments to the brotherhood. Purifying the doctrine by suppression of heresy he seized bhikkhus dwelling in the Abhayagiri (vihära), sixty in number, who had turned to the Vetulya-doctrine and were like a thorn in the doctrine of the Buddha, and when he had excommunicated them, he banished them to the further coast. A bhikkhu from the Cola people, named Samghamitta, who was versed in the teachings concerning the exorcism of spirits, and so forth, had attached himself to a thera banished thither, and he came hither embittered against the bhikkhus of the Mahävihära.
When this lawless (bhikkhu) had thrust himself into an assembly in the Thuparama and had refuted there the words of the thera living in the parivena of Samghapala, namely the thera GOTHABHAYA, uncle of the king on the mother’s side, who had addressed the king with his (old) name, be became a constant guest in the king’s house.’ The king who was well pleased with him entrusted his eldest son Jetthatissa and his younger son Mahasena, to the bhikkhu. And he made the second his favourite, therefore prince Jetthatissa bore ill-will to the bhikkhu.
After his father’s death JETTHA TISSA became king. To punish the hostile ministers who would not go in procession with him, at the performing of the king’s funeral rites, the king himself proceeded forth, and placing his younger brother at the head and then the body following close behind, and then the ministers whilst he himself was at the end (of the procession), he, when his younger brother and the body were gone forth, had the gate closed immediately behind them, and he commanded that the treasonous ministers be slain and (their bodies) impaled on stakes round about his father’s pyre.
Because of this deed he came by the surname ‘the Cruel’. But the bhikkhu Samghamitta, for fear of the king, went hence at the time of his coronation, when he had taken counsel with MAHASENA, to the further coast awaiting the time of (MAHASENA’s) consecrating.
He (JETTHA TISSA) built up to seven stories the splendid Lohapasada, that had been left unfinished’ by his father, so that it was now worth a koti (pieces) of money. When he had offered there a jewel worth sixty thousand, Jetthatissa named it the Manipasada.
He offered two precious gems to the Great Thüpa, and he built three gateways to the temple of the great Bodhi-tree. When he had built the vihara Pacinatissapabbata the ruler gave it to the brotherhood in the five settlements.
The great and beautiful stone image that was placed of old by Devanampiyatissa in the Thuparama did king Jetthatissa take away from the Thuparama, and set up in the Arama Pacinatissapabbata. He bestowed the Kalamattika-tank on the Cetiyapabbata (vihara), and when he celebrated the consecrating festival of the vihära and the pasada and (held) a great Vesakha-ceremony he distributed the six garments among the brotherhood, in number thirty thousand. Jetthatissa also made the Alambagama-tank. Accomplishing thus many works of merit, beginning with the building of the pasada the king reigned ten years.
Thus, reflecting that sovereignty, being the source of manifold works of merit, is at the same time the source of many an injustice, a man of pious heart will never enjoy it as if it were sweet food mixed with poison.
Here ends the thirty-sixth chapter, called ‘The Thirteen Kings’, in the Mahavamsa, compiled for the serene joy and emotion of the pious.
ch 37CHAPTER XXXVII
KING MAHASENA
AFTER king JETTHA TISSA’s death, his younger brother MAHASENA ruled twenty-seven years as king. And to consecrate him as king, the thera Samghamitta came thither from the further coast, when he heard the time (of Jetthatissa’s death). When he had carried out the consecration and the other ceremonies of various kihd**, the lawless (bhikkhu) who would fain bring about the destruction of the Mahavihara won the king to himself with the words: ‘The dwellers in the Mahavihara do not teach the (true) vinaya, we are those who teach the (true) vinaya, O king’, and he established a royal penalty: ‘Whosoever gives food to a bhikkhu dwelling in the Mahavihara is liable to a fine of a hundred (pieces of money).’**
The bhikkhus dwelling in the Mahavihara, who thereby fell into want, abandoned the Mahavihara, and went to Malaya and Rohana. Thus was our Mahavihara desolate for nine years and empty of those bhikkhus who (else) had dwelt in the Mahavihara. And the unwise thera persuaded the unwise king: ‘Ownerless land belongs to the king,’ and when he had gained leave from the king to destroy the Mahavihara, this (bhikkhu), in the enmity of his heart, set on people to do so.
An adherent of the thera Samghamitta, the ruthless minister Sona, a favourite servant of the king, and (with him) shameless bhikkhus, destroyed the splendid Lohapasada seven stories high, and carried away the (material of the) various buildings from hence to the Abhayagiri (vihara), and by means of the many buildings that were borne away from the Mahävihära the Abhayagiri-vihara became rich in buildings. Holding fast to his evil friend, the thera Samghamitta, and to his servant Sona, the king wrought many a deed of wrong. The king sent for the great stone image from the Päcinatissapabbata (vihära) and set it up in the Abhayagiri (vihra). He set up a building for the image, a temple for the Bodhitree, a beautiful relic-hall and a four-sided hall, and he restored the (parivena) called Kukkuta. Then by the ruthless thera Samghamitta was the Abhayagiri-vihara made stately to see.
The minister named Meghavannabhaya, the friend of the king, who was busied with all his affairs, was wroth with him for destroying the Mahavihara; he became a rebel, and when he had gone to Malaya and had raised a great force, he pitched a camp by the Düratissaka-tank.
When the king heard that his friend was come thither, he marched forth to do battle with him, and he also pitched a camp.
The other had good drink and meat, that he had brought with him from Malaya and thinking: ‘I will not enjoy it without my friend the king,’ he took some, and he himself went forth alone by night, and coming to the king he told him this thing. When the king had eaten with him, in perfect trust, that which he had brought, he asked him: ‘Why hast thou become a rebel?’ ‘Because the Mahavihara has been destroyed by thee’ he answered. ‘I will make the vihara to be dwelt in yet again; forgive me my fault,’ thus spoke the king, and the other was reconciled with the king. Following his counsel the king returned to the capital. But Meghavannabhaya, who persuaded the king (that it was fitting to do this), did not go with the king that be might collect in the meantime the wherewithal to build.
One of the king’s wives, who was exceedingly dear to him**, the daughter of a scribe, grieved over the destruction of the Mahavihara,** and when she, in bitterness of heart, had won over a labourer to kill the thera who had destroyed it, she caused the violent thera Samghamitta to be done to death as he came to the Thuparama to destroy it. And they slew likewise the violent and lawless minister Sona. But when Meghavannabhaya’ had brought the building-materials (that he bad collected), he built several parivenas in the Mahavihara. When this fear had (thus) been calmed by Abhaya the bhikkhus coming from here and there again inhabited the Mahavihara. But the king made two bronze images and set them up on the west side of the temple of the great Bodhi-tree.
Being well-pleased with the hypocrite, the plotter, the lawless thera Tissa, his evil friend, who dwelt in the Dakkhinarama, he, although he was warned, built within the boundaries of the Mahavihara, in the garden called Joti, the Jetavana-vihara. Then he called upon the brotherhood of monks to do away with their boundaries, and since the bhikkhus would not do this, they abandoned the vihara. But now, to make the shifting of the boundary void of effect, if others should seek to do this, certain bhikkhus hid themselves in various places.’
Thus was the Mahavihara abandoned for nine months by the bhikkhus, and the other bhikkhus thought: ‘We will begin to shift (the boundaries).’ Then, when this attempt to shift the boundary was given up,’ the bhikkhus came back hither and dwelt again in the Mahavihara. But within the brotherhood of bhikkhus a complaint touching an offence of the gravest kind was raised against the thera Tissa, who had received the (Jetavana) vihára. The high minister, known to be just, who decided (the matter) excluded him, according to right and law, from the order, albeit against the king’s wishes.
The king built also the Manihira-vihara and founded three vihäras, destroying temples of the (brahmanical) gods: the Gokanna (vihara), (and another vihara) in Erakavilla, (and a third) in the village of the Brahman Kalanda; (moreover be built) the Migagama-vihara and the Gangasenakapabbata (vihara). To the west, he built the Dhatusenapabbata (vihara); the king founded also the great vihãra in Kokaväta. He built the Thuparama -vihara and the Hulapitthi (vihara) and the two nunneries, called Uttara and Abhaya. At the place of the yakkha Kalavela’ he built a thüpa, and on the island he restored many ruined buildings. To one thousand samghattheras he distributed alms for theras, at a cost of a thousand (pieces of money), and to all (the bhikkhus he distributed) yearly a garment. There is no record of his gifts of food and drink.
To make (the land) more fertile, he made sixteen tanks, the Manihira, the Mahagama, the Challüra, and the (tank) named Khanu, the Mahamani, the Kokavata and the Dhammaramma-tank, the Kumbalaka and the Vahana, besides the Rattamalakandaka, the tank Tissavaddhamanaka, that of Velangavitthi, that of Mahagallaka, the Cira-tank and the Mahadaragallaka and the Kalapasana-tank. These are the sixteen tanks. On the Ganga he built the great canal named Pabbatanta.
> Thus did he gather to himself much merit and much guilt.