It is thought that the term 'tempura' was initially a general description of oil-cooked dishes introduced from overseas to Kyushu region and Okinawa Prefecture and became widely used to refer to any sort of food prepared using hot oil, including some already existing Japanese foods such as satsuma age (a fried fish cake which is made without batter.)
「天ぷら」とは当初、海外から九州・沖縄県方面に入ってきた油料理の総称であったとされ、後には薩摩揚げ等の、以前より日本にあった油料理も含めた名称となった。