Pangaea - Why did all the land mass form in one area?
The formation and break up of supercontinents have happened throughout Earth's history in almost a cyclical manner. There may have been many others supercontinents before Pangaea and the total number of such is uncertain. The 4 last supercontinents are: Nuna (some other people call it Columbia) that was present in the period 2.0–1.8 Ga (billion years ago or 1000 million years ago, if you use the long notation); Rodinia that formed around 1.1 Ga and lasted until about 750 Ma; Pannotia that lasted 650-560 Ma; and finally, Pangaea.

The location of the supercontinents seems to have varied throughout Earth's history and it doesn't seem likely that there was something special about the location of Pangaea, except the underlying forces of plate tectonics. 

Here is good animation of the evolution in time of the different supercontinents.