Karjala bordered Mynämäki, Mietoinen, Eura, Yläne and Laitila.

Karjala is relatively forested in comparison to Mynämäki and especially Mietoinen, which are mostly former seafloor converted into farmland.

[1] [2] The name of Karjala may be related to the word karja (cattle), most likely indirectly, possibly through the village name Karjakoski in Mynämäki.

The upper reaches of the rivers Mynäjoki and Laajoki were settled in the 13th century.

In the 1960s, it was the least industrialized municipality in Finland Proper, 3/4 of its inhabitants practiced agriculture or forestry.