Karachi

Karachi was a city located in India in 1930. (AUDIO: Storm Warning) By the time Tarak Ital grew up there in the 21st century, it had become a part of Pakistan, (TV: The Waters of Mars) due to the Partition of India in 1947. (TV: Demons of the Punjab)

The pilot Amy Johnson stopped off in Karachi on her attempt to set the speed record from England to Australia. (COMIC: A Wing and a Prayer)

In 1930, the R101 left London, supposedly bound for Karachi. Aboard were two stowaways: the Eighth Doctor and Charlotte Pollard. (AUDIO: Storm Warning)

Behind the scenes
In 1930, when A Wing and a Prayer and Storm Warning are set, the real life country of Pakistan had not yet been created. At that point in the real world, all of modern-day India, and Pakistan were a part of British India, or India for short.

2018's Demons of the Punjab clarifies about the Partition which led to the creation of Pakistan.

In The Waters of Mars, a fictional on screen news article about Tarak Ital describes Tarak as having grown up in "Karachi, Pakistan" after he was born in 2026.