Weiqi / Go

Weiqi, or Go, is a positional game, where the aim is to enclose territory. The game is one of placement only (stones don't move once placed on the board), and so is fully strategical. The winner is the player who encloses most territory, and captures most stones.

Weiqi's origin lies in China, and the earliest written record dates from roughly 500BC, making the game at least 2,500 years old. As such, given it is very popular and commonly played to this day, it may well be the board game with the longest continuous playing history.

The bamboo xiangqi board I got some years ago has a weiqi board on the reverse.

And it was easy enough to get a set of black and white Go stones for it, and so complete the game.