town, east-central Bulgaria, on the Tundzha (Tundja) River. North of the present town are the ruins of Kabyle (or Cabyle), which originated as a Bronze Age settlement in the 2nd millennium BC and was conquered by the Macedonians under Philip II in 342–341 BC. Taken by Rome in 72 BC, Kabyle became a city in the Roman province of Thrace, governing the middle reaches of the Tundzha (ancient Tonsus) and serving as a rest stop on the road to Adrianople (now Edirne). It was the seat of a bishopric in the 4th century AD and disappeared in the 6th century. Finds from excavations at Kabyle are in the Regional Museum of Yambol.

Between the 11th and the 14th century, the present site was called Diampolis; from the 15th to the 19th century under the Turks, it was referred to as Yamboli. The town has ruins of a notable stone mosque. Yambol's industries produce textiles, machinery for footwear manufacture, ceramics, furniture, processed foods, wines, and beverages. Pop. (2004 est.) 79,665.