Assenovgrad has a millennia-old cultural and historical heritage.

The favourable combination of the mountain and the plain, the mild climate, the fertile soil, and also being the entrance of the most convenient pass through the Rhodopes, are the reasons why the Assenovgrad region has been populated since earliest antiquity. One of the most interesting prehistoric objects on the municipality's territory is situated in the village of Dolnoslav in the Lopkite area. The first and for now the only Neolithic cult centre in Bulgaria and the whole world, which served the religious and other spiritual needs of the whole Southern Bulgaria's prehistoric inhabitants, was discovered and researched there.

According to archaeological data, a Thracian settlement, which was preserved in the Roman period, existed in the site of the present town. There is no evidence of the antique town's name.

There are numerous monuments left after the Thracians, which testify to their rich material and spiritual culture. The Thracian rock sanctuaries are exclusively interesting not only for the specialists, but also for the tourists. Four sanctuaries to the Thracian Horseman - the most worshipped deity by the Thracians in the Roman era - were discovered in the Assenovgrad region.

The medieval Assenovgrad shared the region's turbulent fate and the vicissitudes of the battles between Bulgaria and Byzantium, in which it changed its owner many times. The name Stenimachos occurs for the first time in the Statutes of the Bachkovo Monastery, made up in 1803 by order of the Byzantine military leader Grigoriy Bakouriani, who founded the monastery. He also ordered the building of an inn and a fortress for the town's protection. Later on the settlement was mentioned in the Crusades' chronicles as Stanimaco, Estanimac or Scribencion.

In 1230, after the Klokotnitsa Battle, King Ivan Assen II strengthened and enlarged the fortress, which was then called Petrich. He perpetuated his deed in an inscription carved in a rock above the entrance of the fortress, which was later called Assen's Fortress. The town was renamed from Stanimaka to Assenovgrad in his honour in 1934.

After the Russian -Turkish War in 1878, the town remained within the boundaries of Eastern Roumelia and was made a separate administrative unit. The town participated with more than 2 000 of its inhabitants in the Union of Eastern Roumelia with the Bulgarian principality in 1885.

The reputation of the Assenovgrad region as a sacral centre formed in antiquity was further development by the arrival of the Christian religion and culture. The syncretism between the existing cults and the new religion made its adoption easier. The churches and monasteries had to perform directly the spiritual reform and their intense building started for that reason.