Which Indian ruler is known for convening a great religious assembly at Prayag (modern Allahabad) every five years?

Introduction / Context:
Prayag (modern Allahabad, now officially Prayagraj) has long been considered a sacred confluence of rivers and a major pilgrimage site in India. Several rulers held religious gatherings there, but one particular king of north India is remembered for organising a grand religious assembly at Prayag every five years. Identifying this ruler is a frequent exam question because it connects political history with religious and cultural practices in early medieval India.

Given Data / Assumptions:

• The place in question is Prayag, an important pilgrimage centre.
• The event is a great religious assembly held every five years.
• The options list Ashoka, Kanishka, Harshavardhana and Chandragupta Vikramaditya.
• We assume students are aware that different rulers held councils and gatherings in various cities (e.g., Ashoka at Pataliputra, Kanishka at Kashmir).

Concept / Approach:
Harshavardhana, who ruled north India in the 7th century CE from Kannauj, is known for holding a religious assembly at Prayag every five years. This gathering brought together devotees, ascetics and representatives of different religious traditions, reflecting Harsha's policy of tolerance and patronage. Ashoka is associated with Buddhist councils in places like Pataliputra; Kanishka convened a famous Buddhist council near Kashmir; Chandragupta Vikramaditya (Chandragupta II) is known for expanding the Gupta Empire and patronising arts, but not for a five-yearly Prayag assembly. Therefore, Harshavardhana is the correct answer.

Step-by-Step Solution:
Step 1: Identify Harshavardhana as the ruler of Kannauj during the early 7th century CE. Step 2: Recall from historical accounts, including those of the Chinese traveller Xuanzang (Hsuan-tsang), that Harsha held a great religious assembly at Prayag every five years. Step 3: Recognise that this assembly was meant to distribute alms and honour various religious communities, including Buddhists, Hindus and others. Step 4: Distinguish this event from the Buddhist councils of Ashoka, which were held at other locations and not specifically at Prayag every five years. Step 5: Note that Kanishka's council was convened in the Kashmir region and that Chandragupta Vikramaditya is not associated with such cyclical assemblies at Prayag. Step 6: Conclude that Harshavardhana is the ruler described in the question.

Verification / Alternative check:
Textbooks that cover Harsha's reign often recount the vivid description given by Xuanzang of the Prayag assembly. They mention that Harsha gave away enormous wealth in charity during these gatherings and that they took place at an interval of five years. No similar description is linked to Ashoka, Kanishka or Chandragupta Vikramaditya in relation to Prayag, confirming Harsha as the correct choice.

Why Other Options Are Wrong:

• Ashoka: Famous for his Buddhist councils, particularly the Third Buddhist Council at Pataliputra, not for a recurring religious assembly at Prayag.
• Kanishka: Known for the Fourth Buddhist Council in Kashmir, again not for a periodic Prayag assembly.
• Chandragupta Vikramaditya: A Gupta emperor known for military and cultural achievements, but there is no major historical tradition of him holding five-yearly religious assemblies at Prayag.

Common Pitfalls:
Students often mix up different types of religious gatherings and councils, especially when many kings are associated with Buddhist or religious assemblies. It is important to tie each ruler to the correct place: Ashoka with Pataliputra and other sites, Kanishka with Kashmir, and Harsha with Prayag's five-yearly grand assembly. Remembering Xuanzang's account of Harsha's charity at Prayag can help fix this association in memory.

Final Answer:
The ruler who held a great religious assembly at Prayag every five years was Harshavardhana.