The convocation of an assembly at Kannauj was one of the most significant events of the reign of Harsha. The purpose of this assembly was to simplify the doctrines of Mahayanism. This assembly was convened in 643 A.D. It was attended by kings of eighteen countries, 3000 Brahmanas and Jains, 3000 Buddhist monks of Mahayan and Hinayan sects and 1000 Buddhist monks of Nalanda Vihara. The famous Chinese traveler, Hiuen Tsang was also present and presided the assembly.

According to historians Harsha had built a special building for the purpose of assembly.

The proceedings of assembly started with a procession, which was led by a statue of Buddha and Harsha and Bhaskarvarman, were walking serving the statue of Buddha in the form of Sakra and Brahma. They were followed by Hiuen Tsang and other scholars. When this procession reached the assembly house the statue of Buddha was established at a high place and it was worshipped.

Thereafter Hiuen Tsang was appointed as the president of the assembly and the proceedings began when the discussions took a bad trend, Hiuen Tsang stated, "If there is any one who can find a single word in the proposition contrary to reason or is above the entangled or argument then at the request of the support. I offer my head as a recompense."

This created turmoil in the assembly and none dared to challenge the Chinese travelers. It is obvious that Hiuen Tsang had full support of Harsha who had declared that any one harming the Dharmacharya would be beheaded and any one speaking against him will lose his tongue. Thus out of fear of Harsha, none spoke against the said declaration.

After the assembly was concluded, a procession was again taken out. Hiuen Tsang was shown great reverence and was referred as 'Mahayana deva' and 'Moksha deva'.