No offence to the Hokkien tongue but I doubt Hokkien has alot in common with ancient Tang. Hokkien, together with Cantonese, Foochow, Teochew, Wu (Shanghaiese), Gan and Xiang, probably has alot more in common with the languages of ancient Nan Yue Kingdom than with ancient Tang tongue. The theories in the earlier posting have been repeated many times but that does not mean they are true. I suspect they are manifestation of Hokkien pride meant to identify the more peripheral present with a glorious metropolitan past.
There is a lot of historical evidence that up to 1000 A.D., Fujian and most of southern China was still largely inhabitated by the original Nan Yue tribes - in Fujian, specifically Min Yue. It is the fall of Tang and later of Song, that led to repeated wave of northern Han Chinese migration to the south that changed the demographic landscape of the region. The Hokkien people of today is probably a mixture of Min and Han.
Whilst it was true that the North was invaded by Mongols and Jurchens, these peoples speak languages of the Altalic-Uralic and other linguistic groups which are totally different from the Sino-Tibetan group of languages that Mandarin, Hokkien, Cantonese and various southern dialects belong to. In any case, the population of these nomadic tribes was too small to have significant impact on Mandarin apart from some specialised terms relating to military bureaucracy (e.g., qi or banner) and Beijing (e.g. hutong).
In fact, Hokkien's links with Nan Yue makes it a more exotic tongue that identifies itself closely with the diverse cultures of Southeast Asia. This is especially relevant considering the Fujian's historical maritime links with the region.
My 2 cents worth.
--- On Thu, 1/1/09, Beng Kiat Lee <email@example.com> wrote: