Prior to the destruction of the Second Temple in 70 CE, the primary areas known to contain Jewish Diaspora communities were mainly around the Mediterranean region, specifically in places like Rome, Alexandria, and other cities with significant interaction and trade.
Of the options provided, Central Asia is historically known to have had some Jewish communities, especially along trade routes such as the Silk Road.
The other regions mentioned—Great Britain, Japan, and Southern Africa—did not have notable Jewish Diaspora communities at that time. Therefore, the correct answer would be:
Central Asia.