Numerous rock-cut tombs have been found around the village. Clermont-Ganneau identified Ein Siniya with Biblical Jeshanah and Isana of Josephus, but modern authors place that at Kh. el-Burn. Ein Siniya has usually been identified as the Crusader village Aineseins, which was one of 21 villages given by King Godfrey as a fief to the canons of the Holy Sepulchre. However, C. N. Johns, writing in 1939, thought that Aineseins was located by Tel Beit Shemesh. Claude Reignier Conder and Herbert Kitchener wrote in 1882 that a small Crusader fort appeared to have been situated there, however, this has not been verified by later sources.
Ottoman era
During Palestine's rule by the Ottoman Empire, Ein Siniya was located in the sheikhdom of Bani Zeid, in the Jerusalem Sanjak. In 1556, it was the smallest village in the sheikhdom, having under ten households. Potsherds from the early Ottoman period have been found. In the Ottoman census of 1596, Ein Siniya was a part of the nahiya of Jerusalem, which was under the administration of the Jerusalem Sanjak. The village had a population of 12 households, all Muslim, and paid taxes on wheat, barley, olives, vineyards, fruit trees, occasional revenues, beehives and/or goats; a total of 4,300 akçe. Prior to the 1834 peasants' revolt, Ein Siniya belonged to the Bani Murrah tribe. After the revolt, the sheikhs were appointed by Ibrahim Pasha. In 1838, Biblical scholar Edward Robinson found the village to be surrounded with vineyards and fruit-trees. There were also gardens of vegetables, watered from a well. It was further noted as Muslim village, located in the Beni Murrah district, north of Jerusalem. In 1870, the French explorerVictor Guérin visited the village, which he found to have two hundred inhabitants. Socin found from an official Ottoman village list from about the same year that Ein Siniya had 57 houses and a population of 218, though the population count included men only. In 1882, the PEF's Survey of Western Palestine described Ain Sinia as a small village, but of "undoubted antiquity." Early in the 20th century, Ain Sinya was "practically" the property of a wealthy Arab native of Jerusalem who influenced authorities to build a carriage road next to Ein Siniya to benefit the village. In 1907 the population was Muslim. At the same time it was noted that Ein Siniya, unlike other Arab villages in the area, grew mulberry and walnut trees in abundance instead of olive or fig groves. In 1896 the population of 'Ain Sinja was estimated to be about 237 persons. In the early 1900s Moshe Sharett lived in the village with his family, for two years.
In the 1922 census of Palestine, conducted by the British Mandate authorities, the population numbered 114, Muslims, increasing in the 1931 census to 288, in 59 inhabited houses. 15 villagers were Christian, the rest Muslim. In 1945 statistics Ein Siniya had a population of 330 inhabitants; 310 Muslims and 20 Christians, and a total land area of 2,724 dunams, most of which was Arab-owned. Its built-up area consisted of 21 dunams, while 2,404 dunams were cultivated. 1,856 dunams were allocated for plantations and irrigable land, and 548 for cereals.
Since the Six-Day War in 1967, Ein Siniya has been under Israeli occupation. After the 1995 accords, 2,578 dunum of village land is defined as Area B land, while the remaining 618 dunum is defined as Area C. Much of the population fled during the war and only by 1982 did the population reach roughly what it was in 1945, 333. It grew to 482 in 1987, and then 533 in the census carried out by the Palestinian Central Bureau of Statisticsa decade later. The main cause of the growth of Ein Siniya, which was nearly empty after the 1967 war, was an influx of Palestinian refugees, who by 1997 constituted over half of the population. According to the PCBS, Ein Siniya had a population of 702 in 2004, rising to 753 in mid-year 2006. In the 2007 PCBS census, there were 711 people living in the town. 'Ein Siniya residents are from several families, mainly the Ghanimah, Abu Al-Sheikh, Samhan, Ma'alla, Khater, Abu al Hajj, Dar Ali, Bazrooq, Mousa and Al Hallaq families.
