Carved out of Aizawl district, Kolasib sits where Mizoram meets Assam
Background
The northern tip of Mizoram is Kolasib district, and road and rail links from Assam into the State run through this stretch. Its northern boundary is with the Cachar district of Assam, so this is where Mizoram meets its larger neighbour. The district was created in the year 1998 by carving it out of what was then Aizawl district. Its own administration notes that it was made simply by raising an existing sub-division to district rank. Kolasib is therefore one of the newer districts of a State whose district map has been redrawn more than once. Being the gateway from Assam gives this district weight out of proportion to its size. Traffic between Aizawl and the rest of the country passes this way.
In plain words
Parent district The district a new district is carved out of — The older district whose area was divided to make a new one.