If they are similar to khipus (used for accounting) perhaps we're looking at the invention of a central bank. Think about it, the village has a hard year, so t

If they are similar to khipus (used for accounting) perhaps we're looking at the invention of a central bank. Think about it, the village has a hard year, so they collectively borrow grain from another village. How do you settle disputes about exactly how much was borrowed? You build a big thing on the edge of town that everyone can see and can't destroy without a bunch of effort.