After the split from the supercontinent, the individual continents underwent a number of changes of their shoreline. For example, the constant flow of water "smoothed" the surface, which meant that in some parts the land decreased (was washed away by the currents) and in other parts the land increased with the accumulation of the material that the currents brought.
This changed the shape of the continents in a way that they no longer "fit" together perfectly.
The three things that helped the Tang Dynasty was:
Silk road, trading colonies and shipbuilind.
The silk road was a trading routes connecting the East and West.
The trading colonies dealt with cotton, rice, tobacco, indigo (dye), lumber, furs, and farm products; that is what most of the people traded back in the tang dynasty. They will trade these things for food, clothing, books, medicine and sometime homes.
The shipbuilding made a huge part because the people would build ships to trade things to different lands. Usually when they trade more things to different lands they'll get more money.
Hope this helped :)
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A shortage of money
-There was a limited supply gold and other hard currency across the colonies. Also, Paper money was not issued by the government and was not recognized across colonial boundaries. As a result, exchange was mostly conducted through barter trade
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