There were certainly vast differences in wealth before currency. Our u/Trevor_Culley explains the history of coinage here (and here with more of a focus on Egypt), noting that many early civilisations existed without it. And if we use Ancient Greece as an example, u/Iphikrates mentions in this thread when discussing taxation in that time that there were huge differences in wealth between the elites and the poor since before coinage was introduced. As he elaborates in this discussion on Greek military and economic development, wealth disparity lessened in the city-states during the 6th century (which was during the time coinage became more common)