According to oral tradition of the residents, the founder of the Kabha clan moved from Beit Jibrin to Ya'bad in the 18th century. Some of the clan members left Ya'bad in the mid-19th century searching for sources of living, and they found a spring with pastures for their cattle and bought the lands around it and established Barta'a. Ein as-Sahla was established as a daughter village of Barta'a in the 19th century.
During the 1948 Arab–Israeli War the village and the surrounding area came under Iraqi control. In March 1949 Jordanian forces replaced the Iraqi forces in Wadi Ara. On 3 April 1949 Israel and Jordan signed an armistice agreement, in which Israel would receive the Wadi Ara area. After Israeli independence, the population of the village increased and martial law was implemented, which led to the settlement becoming a separate village in 1963. In 1973 the first mosque, named Abu Bakr Al-sidik, was built and in 1989 the second one, named Al-Huda Mosuqe, was built. Ein as-Sahla lacked municipal status after the establishment of Israel and was under the administration of mukhtars appointed by the Interior Ministry. In 1992, the Interior Ministry established the Nahal Ironregional council, which included Ein as-Sahla and seven other villages. The locals objected to this administrative arrangement, and sought independent municipal status for each village. To allay local concerns, the Interior Ministry established an investigative committee to examine other options, and in 1996, decided to split the regional council into two local councils, Ma'ale Iron and Basma, which includes Ein as-Sahala.
Education
Ein as-Sahla has five kindergartens and an elementary school with 19 classes.
Geography
Ein as-Sahla occupies Mount Al-Khataf, which overlooks Wadi Ara. In the middle of the village there is a spring which gives it its name "Spring of the Plain". The village has a neighbourhood on the foot of the hill which has 350 residents. The village is surrounded by nature, which attracts tourists. The only established entrance to the village is through Ar'ara.
Sports
Ein as-Sahla has a local football club called "Hapoel Ein Sahla", participating in Liga Bet. The club has an adult and a youth team and they host matches in a soccer fields located in Barta'a.