The granting of land by the aristocrats and king to the temples led to solidarity between the land-owners, the state and the wealthy temples' incumbent clergy. In fact, the state ultimately enforced the Sangha's appropriation of rice. For instance, monks led a revolt against the colonial powers in 1848 when the British decided to stop enforcing the "customary" rice tithe of the sharecroppers of temple lands to their monastic landlords; the monks were driven to insurgency by their hunger (de Silva, 1941). The accumulation of monastic property in the medeival and colonial periods encouraged the internal differentiation of, and conflicts within, the Sangha, and thus necessitated the growth of strong, centralized sect structures to mediate these conflicts between monks over property, as Gunawardana (1979) shows for medeival Anuradhapura.
These hierarchical sect structures, controlled by wealthy clerical elites, allied politically, economically and through kinship with the aristocracy, also allowed the maintenance of the political and ideological hegemony of these elites over the plebian, propertyless monks at the base; monks and temples not allied with the dominant sects were frequently accused of heresy and became the subjects of clerical and political persecution. Periodically, as the temples became obscenely wealthy and lost their legitimacy for the public, and thus their ability to legitimate the social and political order, ascetic movements split off which attracted pious lay patronage, became rich and powerful, and spawned new reform sects. Even the religious ideologies of these competing monastic groups were never purely "insurgent"; any particular religious expression, being the result of social struggle, necessarily included elements which both potentially undercut and reproduced social power relations.
The monks not only monopolized religious legitimation, but also education. In the pre-colonial period the only formal education available was to be found in the temple. As the sole teachers and knowledge producers for their society, the monks shaped the world views of the people in their own interests, and in the interests of those with whom they were inter-dependent, the aristocracy and royalty. One the main spurs to the anti-colonial/anti-Christian militance of the disenfranchised, low-caste monks of the nineteenth century was the threat to the clerical monopoly on edcuation posed by the Christian missionaries.(4) The missionary school training of an indigenous Tamil and Sinhalese elite to administer Sri Lanka for the British was accompanied by the conversion of these indigenous elites to Christianity. Though the conversion of Sinhalese elites to Christianity threatened even landed, upper-caste monks' organic connection to power, the landless, low-caste sects along the Southern coast were directly economically threatened by this disenfranchisement. The Kandyan, Siyam monks just grumbled, while the low-country plebian monks became leaders in anti-colonial agitation.
Unfortunately it was also in this early anti-colonial period that the low-caste coastal merchant elites, allied with certain fiery monks, drew together the modern Sinhala chauvanist mythos in their struggle against colonialism. The first aspect of the mythos was the claim that the Sinhalese were the pure-blooded descendents of the 'Aryans" who had conquered the darker-skinned "Dravidians" of South India thousands of years before. The Sinhalese were thus the "racial equals" of the Europeans, and, in fact, during the rise of German fascism, some Sinhalese repeated the Nazi call for Aryan racial purity.
Another element was the myth that the Sinhalese race was founded by a North Indian "Aryan" prince named Vijaya who came to Lanka in the 6th century conquering the native aboriginal peoples. Though he and his men married South Indian Dravidians he was supposedly the founder of the pure Sinhala race. In fact, there has been such a degree of intermarriage and cultural intermixing of South Indians and Sinhalese, that it is hardly correct to consider Sinhala culture, language or religion a unified tradition, much less the Sinhalese and Tamils as distinct races.
The Mahavamsa chronicles provided another strand of the Sinhala mythos. The monks who composed the Mahavamsa asserted that the Buddha had entrusted the care of pure Buddhism to the Aryan Sinhalese on this sacred island after driving off the aboriginal "demons" living there; from then on, whenever the island was invaded, it was to be reconquered in the name of Buddhism. The central figure of this "reconquest mythos" is the young warrior Dutugemunu (161-137 B.C.), accompanied by 500 Buddhist monks and a monk-general, as he mounts a relic of the Buddha on the end of his spear and sets out to reconquer Sri Lanka from the South Indian kings. After slaughtering thousands, Dutugemunu is stricken with guilt, and dread of the karmic consequences of his acts. But monks in attendence consoled him that since there had only been one man who had taken Buddhist precepts and another who had taken refuge in the Three Jewels, there had therefore been only one and a half "human" victims.
The origination of a historical literature in Ceylon in the existing form was an intentional act of political relevance. Its object was the propagation of a concept of national identity closely connected with a religious tradition, i.e. the identity of the Sinhalese Buddhists. This idea has shaped the history of Ceylon from the days of the earliest chroniclers to the present day in its particular way. Without the impact of this idea, the remarkable continuity of the cultural as well as of the political traditions in spite of the vicissitudes in the history of the island would have been impossible. Its impact has at the same time, entirely changed the Asokan ideology (the original model for king-Sangha-people unity). For Asoka, the idea of a non-denominational welfare-state was born from the inner conflict of the king resulting from his repentence of the war he had made before his conversion to the Buddhist religion. For the author of the Mahavamsa, on the other hand, the war of Dutthugamani against the Tamil invaders was by no means a problem of religion and morality, but it was an act of justified politics.
Bechert, 1978, p.7
In other words, out of the need to mute the progressive and critical strains in the Buddhist tradition, and develop religious legitimations of the feudal social order, Buddhist monks developed a racial-nationalist ideology. As long as the rulers of Sri Lanka were non-Buddhist and non-Sinhala, such as the British or the English-speaking Sinhalese Christians, this ideology could be turned to the purposes of insurgency; in other words, the ideology, though largely tending to reproduce the social order, included elements which could be used for subversion.
http://www.changesurfer.com/Bud/Sri/Sri.html