About trading goods - everybody needs ammo, alcohol and food. But there are more interesting things. For example one american diplomat wanted to cross Russia in 1918 from Eastern China throu Siberia, Ural, European part of Russia and Ukraina. The country was in chaos of civil war, there were dosen of different local gouvernements and warlords, money were nothing, the normal way of trade was barter. He needed something for barter sutable enough on the whole territory, in any prosperity, political and other conditons, but some common and cheap - not gold or something expensive just not to be killed and robbed. He choose nails... simple nails, different in size and material. He bought full railroad cart of different nails, another for himself and began his travel across fighting ex-Russian Empire. He was sucessful - peasants and workers, merchants and officers, Reds, Whites, local powers and bandits - they all were interested in nails.