Which one of the following was initially the most powerful city state of India in the 6th century B.C. ?

Early sources and syntheses of the mahājanapada period indicate that Kashi (centered on Varanasi) was initially the most powerful city-state at the outset of the 6th century BCE, famed for its wealth, markets and strategic riverside location; it was later subsumed by neighboring Kosala [1]. However, over the subsequent centuries Magadha emerged as the dominant mahājanapada — from the sixth to the fourth centuries BCE it rose to preeminence because of productive agriculture, access to iron, war elephants, riverine communications and the policies of ambitious rulers like Bimbisara and Ajātaśatru [2].

Sources

1. [1] https://ebooks.inflibnet.ac.in/icp01/chapter/mahajanapadas-rise-of-magadha-nandas-invasion-of-alexander/
2. [2] THEMES IN INDIAN HISTORY PART I, History CLASS XII (NCERT 2025 ed.) > Chapter 2: Kings, Farmers and Towns > 2.2 First amongst the sixteen: Magadha > p. 31