Sihai

This name, Four Seas (四海 pinyin sìhǎi), is sometimes used to refer to China. At other times it simply means "the country". It came from the ancient notion that land was surrounded by sea in all four directions.

This group of names derives from Khitan, an ethnic group that originated in Manchuria and conquered Northern China. Due to long domination of Northern China by these non-Chinese conquerors, it was considered by northwestern people as the land of the Khitan. In English and in several other European languages, the name "Cathay" became widely used for all of China largely as a result of translations of the adventures of Marco Polo, which used this word for northern China.