Harsha, the great ruler of north India in the seventh century CE, was finally defeated by which contemporary ruler, marking a check to his further southward expansion?

Introduction / Context:
Harsha, also known as Harshavardhana, was one of the most powerful rulers of north India in the early seventh century CE. His empire stretched over large parts of the Gangetic plain, and he is remembered for his patronage of religion, literature and culture. However, his ambition to extend his rule further towards the Deccan was checked by a strong contemporary ruler in the south. This question tests knowledge of the political geography of early medieval India and the conflict that limited Harsha expansion.

Given Data / Assumptions:
• The question is about Harsha, a seventh century CE north Indian ruler. • We are asked to identify who defeated him and blocked his southern advance. • The options list Sasanka, King of Valabhi, Bhaskarvarman and Pulkesin II. • We assume awareness of major contemporary kingdoms, especially in the Deccan.

Concept / Approach:
To answer this, we recall that Harsha tried to expand his influence southward beyond the Narmada River. At that time, the most powerful Deccan kingdom was the Chalukya dynasty of Badami. Its famous ruler, Pulakeshin II (often written as Pulkesin II in older texts), successfully resisted Harsha invasion. An important inscription, the Aihole inscription, describes how Pulakeshin II checked Harsha on the banks of the Narmada River and forced him to retreat. Other rulers listed in the options either supported Harsha or were his rivals in the east but did not inflict this decisive defeat.

Step-by-Step Solution:
1. Place Harsha in time and space as a ruler of north India around the early seventh century CE. 2. Recall that his northern and eastern influence extended widely, but his attempt to move southwards faced resistance. 3. Identify the main Deccan power of the period as the Chalukyas of Badami under Pulakeshin II. 4. Remember that Pulakeshin II is famous for defeating Harsha on the banks of the Narmada River, a battle that marked the southern limit of Harsha influence. 5. Compare the options: Sasanka of Gauda and Bhaskarvarman of Kamarupa were eastern rulers, while the generic king of Valabhi does not match the well recorded Deccan conflict. 6. Therefore, Pulkesin II (Pulakeshin II) is the correct answer.

Verification / Alternative check:
Standard history texts on early medieval India clearly state that the Narmada River became the boundary between Harsha empire in the north and Pulakeshin II Chalukya kingdom in the south. The Aihole inscription celebrates Pulakeshin II victory over Harsha. This supports the identification of Pulkesin II as the ruler who defeated Harsha and checked his southern campaign.

Why Other Options Are Wrong:
Sasanka: Ruler of Gauda in Bengal, often an adversary of Harsha in the east, but he is not known for defeating Harsha in a major battle that limited Harsha southern expansion. King of Valabhi: A regional ruler in western India without a famous recorded direct defeat of Harsha similar to the Narmada battle against Pulakeshin II. Bhaskarvarman: Ruler of Kamarupa in Assam, an ally of Harsha rather than his adversary.

Common Pitfalls:
Learners sometimes confuse the different regional rivals of Harsha and may think that because Sasanka opposed him in Bengal, he must also be the one who defeated him. Another mistake is to overlook the specific Deccan context and the significance of the Narmada frontier. It is important to remember that Harsha major military check came from the Chalukya king Pulakeshin II in the south, not from his eastern rivals.

Final Answer:
Harsha was defeated and his southward expansion checked by Pulkesin II, the powerful Chalukya ruler of the Deccan.