In spite of ambiguous references to Shailendra connections overseas, there is no solid evidence that the territories of the central Javanese rulers at this time extended far beyond central Java, including its north coast. Yet the agricultural wealth of this small kingdom sustained vast religious undertakings; the monuments of the Kedu Plain are the most famous in Indonesia. The Borobudur temple complex, in honour of Mahayana Buddhism, contains 2,000,000 cubic feet (57,000 cubic metres) of stone and includes 27,000 square feet (2,600 square metres) of stone bas-relief. Its construction extended from the late 8th century to the fourth or fifth decade of the 9th. Shiva's great temple at Prambanan, though not associated with the Shailendra family, is less than 50 miles (80 kilometres) away, and an inscription dating to 856 marks what may be its foundation stone. The two monuments, which have much in common, help to explain the religious impulses in earlier Javanese history.

Borobudur is a terraced temple surmounted by stupas, or stone towers; the terraces resemble Indonesian burial foundations, indicating that Borobudur was regarded as the symbol of the final resting place of its founder, a Shailendra, who was united after his death with the Buddha. The Prambanan temple complex is also associated with a dead king. The inscription of 856 mentions a royal funeral ceremony and shows that the dead king had joined Shiva, just as the founder of the Borobudur monument had joined the Buddha. Divine attributes, however, had been ascribed to kings during their lifetimes. A Mahayana inscription of this period shows that a ruler was said to have the purifying powers of a bodhisattva, the status assumed by the ruler of Shrivijaya in the 7th century; a 9th-century Shaivite inscription from the Kedu Plain describes a ruler as being "a portion of Shiva." 

The divine qualities of these kings, whether of Mahayana or of Shaivite persuasion, had important implications in Javanese history and probably in the history of all parts of the archipelago that professed the forms of Indian religion. The ruler was now and henceforth seen as one who had achieved union with the supreme god in his lifetime. Kingship was divine only because the king's soul was the host of the supreme god and because all the king's actions were bound to be the god's actions. He was not a god-king; he was the god. No godlike action was more important than extending the means of personal salvation to others, always in the form of union with the god. The bas-relief of the Borobudur monument, illustrating Mahayana texts and especially the Gandavyuha--the tale of the tireless pilgrim in search of enlightenment--is a gigantic exposition of the Mahayana path to salvation taken by the king; it may be thought of as a yantra, or instrument to promote meditation and ultimate union with the Buddha. But Borobudur can also be identified as a circle, or mandala, of supreme mystical power that signified the Void of the Vairocana Buddha according to the Vajrayana persuasion of Tantric Buddhism. The mandala was intended to protect the Shailendra realm for all time. The pedagogical symbolism of the Prambanan temple complex is revealed in its iconography, dominated by the image of the four-armed Shiva, the Great Teacher--the customary Indonesian representation of the supreme deity. Prambanan affirms the Shaivite path to salvation; the path is indicated in the inscription of 856, which implies that the king had practiced asceticism, the form of worship most acceptable to Shiva. Shaivism in Java as well as Mahayana Buddhism had become hospitable to Tantric influences. An almost contemporary inscription from the Ratu Boko Plateau, which is not far from the Prambanan complex, alludes to special rites for awakening Shiva's divine energy through the medium of a ritual consort.

Keraton Ratu Boko

These royal tombs taught the means of salvation. The royal role on earth was similar. The kings, not the religious elite, bore the responsibility of ensuring that all could worship the gods, whether under Indian or Indonesian names. Every god in the land was either a manifestation of Shiva or a subordinate member of Shiva's pantheon, and worship therefore implied homage to the king, who was part of the god. The growing together, as a result of Tantric influences, of Shaivism and Mahayana Buddhism meant that, over the centuries, the divine character of the king became continually elaborated. His responsibility was the compassionate one of maintaining his kingdom as a holy land. The bodhisattva-king was moved by pity, as were all bodhisattvas, while the Shiva-like king, as an inscription of the 9th century indicates, was also honoured for his compassion. Compassion was expressed by providing an environment wherein religion could flourish. Keeping the peace, protecting the numerous holy sites, encouraging religious learning, and above all performing purification rituals to render the land acceptable to the gods were different aspects of a single mission: the teaching of the religious significance of life on earth. The lonely status of the ruler did not separate him from the religious aspirations of his subjects; Prambanan provides a recognition of the community of interest between ruler and ruled. The 856 inscription states that a tank of purifying water, filled by a diverted river, was made available as a pilgrimage centre for spiritual blessings. Hermitages had been built at the Prambanan complex, and the inscription states that they were "to be beautiful in order to be imitated."

Prambanan Temple

The great monuments of the 9th century suggest something of the cultural ambience within which events took place. One new development in central Java was that capable local rulers, called raka, were gradually able, when opportunities arose, to fragment the lands of some raka and absorb the lands of others. At the same time, they established lines of communication between themselves and the villages in order to guarantee revenue and preserve a balance between their own demands and the interests of the independent and prosperous agricultural communities. When a ruler manifested divine qualities, he would attract those who were confident that they were earning religious merit when they supported him. Local princes from all over the Kedu Plain constructed small shrines around the main Prambanan temple in a manner reminiscent of a congregation gathered around a religious leader. The inscription of 856 states that they built "cheerfully."