One of the crucial things was the recognition of PRC as China and it's rights over ROC(Taiwan). I am not sure if Pakistan was the first country to do this, but it might have been. During the Ayubid period Pakistan was a model for development, and foreign delegations used to visit Pakistan to asses the changes being implemented. Pakistan had better prospects than most ASEAN countries, who used to look toward it as a model.(According to an old guard Pakistani Bureaucrat)
In the Middle of the Indo/China war, Chinese even offered Pakistan to join the war to liberate Kashmir, realizing the weaker position of the Indians. It was the US that told Pakistan to refrain from such an action.
Another factor is that Pakistan always votes in favor of the Chinese in the UN.
Edited by malizai_ - 03-Mar-2008 at 23:17