Among the following rivers, which one is not mentioned in the hymns of the Rigveda?

Introduction / Context:
This question belongs to Vedic literature and historical geography. The Rigveda, one of the oldest Indian texts, frequently mentions various rivers that were important to the early Vedic people, especially in the north-western part of the Indian subcontinent. Identifying which river is not mentioned in the Rigveda helps you distinguish between rivers central to Vedic culture and those belonging to other regions and later historical contexts.

Given Data / Assumptions:

• The text in focus is the Rigveda.
• We are asked to find the river that does not appear in its hymns.
• Options: Sindhu (Indus), Saraswati, Yamuna, Periyar.
• We assume standard scholarly identifications of Vedic river names.

Concept / Approach:
The Rigveda praises the Sindhu (Indus) and several of its tributaries. Saraswati is described as a mighty river in the Vedic hymns, and Yamuna is also mentioned, though less prominently than some others. Periyar, however, is a river of southern India (mainly in Kerala) and lies far outside the early Vedic geographical horizon, which was centred in north-west India. Therefore, Periyar is the river that is not mentioned in the Rigveda.

Step-by-Step Solution:
Step 1: Recall that Vedic tribes lived primarily in the north-west, along the Indus system and nearby rivers. Step 2: Remember that Sindhu (Indus) is one of the most frequently praised rivers in the Rigveda. Step 3: Note that Saraswati appears in many hymns as a mighty, sacred river. Step 4: Recognise that Yamuna is also mentioned, though less prominently, as a northern river. Step 5: Understand that Periyar is a river in Kerala in south India and does not figure in Rigvedic descriptions. Step 6: Select Periyar as the correct answer.

Verification / Alternative check:
If you consult summaries of “Nadistuti sukta” and other river hymns in the Rigveda, you will see repeated references to Sindhu (Indus), Saraswati, and other northern rivers such as the Vipasha (Beas) and Asikni (Chenab). Yamuna is also locally mentioned. However, no Rigvedic hymn lists Periyar among its rivers, as that river belongs to the far-southern landscape. This geographical mismatch confirms that Periyar is not a Rigvedic river name.

Why Other Options Are Wrong:
Option a (Sindhu) is wrong because the Rigveda strongly praises Sindhu as a mighty river and even uses its name in the generic sense of “river.” Option b (Saraswati) is central to many Rigvedic verses and is described as flowing from the mountains to the sea. Option c (Yamuna) is also referred to in the Rigveda, though not as frequently as some other rivers. Therefore, all three rivers occur in the Vedic text, unlike Periyar, which does not.

Common Pitfalls:
A common pitfall is to assume that Yamuna is only associated with later Puranic and Krishna-related stories and to forget that it is already known in the Rigvedic period. Another mistake is not paying attention to regional geography and assuming that any famous Indian river might appear in the Rigveda. To avoid such errors, remember that the Rigveda is largely limited to north-western India, and southern rivers like Periyar are outside its scope.

Final Answer:
Periyar is the river among the options that is not mentioned in the Rigveda.