Pakistan and India haven’t played a Test series for almost eight years now. As always, the reasons have been largely political.
Before the current stalemate, there was a 10-year-break (in the 1990s). When Pakistan toured India in 1999, the two cricket-crazy nations hadn’t met in a Test series since 1989.
However, the longest gap between a Test series involving these two countries lasted for almost 17 years!
There was no series between Pakistan and India from 1961 till 1978. Both the countries had played three 5-Test-rubbers from 1952 till 1961, but none for the next 17 years.