The Fourth Buddhist Council, which played an important role in the development of later Buddhist schools, was convened during the reign of which king?

Introduction / Context:
Buddhist councils were important gatherings of monks held after the life of the Buddha to recite, preserve and sometimes interpret the teachings. Several councils are mentioned in Buddhist tradition, and each is associated with a particular ruler and period. The Fourth Buddhist Council is particularly significant for the development of Mahayana Buddhism and for the spread of Buddhism beyond India. This question asks which king convened this council.

Given Data / Assumptions:
• The focus is specifically on the Fourth Buddhist Council. • The options include Ashoka, Ajatasatru, Kanishka and Mahapadmananda. • We assume familiarity with which rulers are linked to which councils.

Concept / Approach:
According to most traditional accounts, the First Buddhist Council was held at Rajagriha soon after the Buddha death during the time of Ajatasatru. The Second was at Vaisali. The Third Council is associated with Emperor Ashoka at Pataliputra, where efforts were made to purify the Sangha and send missionaries abroad. The Fourth Buddhist Council, however, is linked with the Kushana king Kanishka and is believed to have taken place in Kashmir or nearby regions. This council is often connected with the deepening of scholastic activity and compilation of commentaries, influencing the later course of Buddhism.

Step-by-Step Solution:
1. List the main councils and their associated rulers. 2. Recall that Ajatasatru is linked with the First Buddhist Council at Rajagriha. 3. Remember that Ashoka, the Mauryan emperor, is associated with the Third Council at Pataliputra. 4. Recognise that Kanishka, the Kushana ruler, is associated with the Fourth Buddhist Council, often held in Kashmir. 5. Mahapadmananda is not linked with any Buddhist council in commonly accepted lists. 6. Therefore, identify Kanishka as the king during whose regime the Fourth Buddhist Council was convened.

Verification / Alternative check:
Standard histories of Buddhism note that Kanishka patronised Buddhism, particularly schools that contributed to Mahayana thought. They record that under his rule, learned monks assembled at a council where Abhidharma texts and commentaries were discussed or compiled. This event is acknowledged as the Fourth Buddhist Council in many traditions, confirming that Kanishka is the correct answer for this question.

Why Other Options Are Wrong:
Ashoka: Patron of the Third Buddhist Council, not the Fourth, and associated with Pataliputra rather than Kashmir. Ajatasatru: Ruler connected with the First Buddhist Council immediately after the Buddha passing, not with later councils. Mahapadmananda: Founder of the Nanda dynasty, important in political history but with no strong traditional association with Buddhist councils.

Common Pitfalls:
A typical error is to pick Ashoka for any question about a Buddhist council because his name is closely linked with the spread of Buddhism. Another confusion arises from mixing up the numbers of the councils and the names of the rulers. A helpful memory pattern is: Ajatasatru with the First, Ashoka with the Third and Kanishka with the Fourth Council. Keeping this sequence in mind makes it easier to answer related questions accurately.

Final Answer:
The Fourth Buddhist Council was convened during the reign of the Kushana king Kanishka.