One method, used a lot in Scandinavian cultures was "hoarding". This is where you take all the money you want to save, find a hidden spot and you bury it. Then when you want to use it you go back and dig it up again.

This method was used a lot throughout history, and many hoards still survive because the owners either forgot or were killed before they could retrieve their money. Heres a link to a hoard they just found in England: http://www.northantstelegraph.co.uk/news/regional/roman-coins-hoard-found-in-cave-1-6162330