What is the China toy that foreigners call "Tangtu"?

First, the "Tangtu" in the foreign population is a jigsaw puzzle, also called a wisdom board.

Second, Tangram is an ancient traditional intellectual game of the Han nationality. As the name implies, it consists of seven chessboards. These seven boards can be combined into many figures (1600), such as triangles, parallelograms, irregular polygons, etc. Players can also combine them into various characters, images, animals, bridges, houses, towers, etc., or some Chinese and English letters. Its history can be traced back to at least the first century BC, and it was basically finalized in the Ming Dynasty. It was widely circulated among Han people in Ming and Qing Dynasties. In Volume 1 of Miscellaneous Knowledge in Leng Lu, Yi wrote: Recently there are seven clever diagrams, five shapes and seven numbers, and there are thousands of variations. Things are small in shape, changing at will, and full of games, which are enough to relieve boredom and break the silence, so secular people like them.

Third, in the18th century, the jigsaw puzzle spread abroad. Needham said that it is one of the oldest pastimes in the East. Up to now, the library of Cambridge University in England still has seven ingenious chess pieces.