This is a copy of the the royal game of Ur, found in Iraq in the 1930s, but over 4000 years old. Rules haven't been found for this specific version, however they've been reconstructed from later versions, found here: https://royalur.net/rules

I personally like the version of the rules from a copy I purchased, which I've added as a photo.

I used 4x2mm round magnets to hold the board halves together when playing and during transport, and also in the case that holds the pieces.