Islamic Republic of Pakistan (modern)
Who & why: the 1971 crisis develops into a nine-month war between Pakistani forces and Bengali nationalist forces backed by Indian military intervention; East Pakistan achieves independence as Bangladesh in December 1971, roughly a quarter-century after Partition first joined the two wings under one state. Pakistan continues from this point as a single, geographically contiguous country, cycling between civilian government and periods of military rule (notably under Zia-ul-Haq in the 1980s and Pervez Musharraf from 1999) while retaining and repeatedly amending its 1956 republican framework. Pakistan and India each administer parts of the disputed Kashmir region, a dispute dating to Partition that remains unresolved.
What it represents: the same green, white-striped, crescent-and-star flag adopted in 1947 continues unchanged into the present day — the flag has now outlasted every other political arrangement in Pakistan's own history.