The Upper Thracian Plain (Bulgarian: Горнотракийска низина, Gornotrakiyska nizina) constitutes the northern part of the historical region of Thrace.
A fertile agricultural region, the Upper Thracian Plain proper has an area of 16,032 square kilometres (6,190 sq mi) and an average elevation of 168 metres (551 ft).
The highest temperature recorded in Bulgaria occurred here: it was 45.2 °C (113.4 °F) at Sadovo in 1916.
Important rivers are the Maritsa and its tributaries, Arda, Tundzha, Stryama, Topolnitsa, and Vacha.
Important cities include Plovdiv, Burgas, Stara Zagora, Pazardzhik, Asenovgrad, Haskovo, Yambol and Sliven.