Explanation

Pakistan purchased Gwadar port from Oman on 8th September 1958.

Gwadar officially became part of Pakistan on 8th December 1958.

Gwadar remained under Omani rule for 174 years from 1783 -1958 

Gwadar Port is situated on the Arabian Sea at Gwadar in Balochistan province.

Opened: 2002 

while 

Pakistan has three big sea ports  It was purchased from Oman in 1958.

Karachi Port,

Muhammad Bin Qasim port

and Gwadar port.