The village stood on flat ground on the coastal plain and was surrounded by hills; Wadi Simsim ran along its southern perimeter. It lay between the coastal highway and a parallel highway that ran from Gaza to Julis. Secondary roads connected Simsim to these highways and to a number of neighboring villages. The village was known as Semsem to the Crusaders. In 1596 Simsim was a village in the nahiya of Gaza (liwa' of Gaza), with a population of 110. It paid taxes on wheat, barley, fruit trees, goats, and beehives. In the late nineteenth century, the village of Simsim was surrounded by gardens. It had a well, a pool, and an olive grove that was planted to the north. Simsim was the hometown of al-Shaykh Sulayman Abd al-Qadir (Abu Ali), one of the leaders of the 1936 revolt against British occupation. It had an overall circular layout, with straight, narrow streets emanating from the center and intersecting with semi-circular ones. Simsim was divided into separate quarters—the largest of which was the northern quarter—by the roads that linked it to the other villages. These roads were also the axes along which it expanded. At the intersection of these axes (the village center) was a mosque. The center also contained a school, founded in 1934 and shared in 1947 with the village of Najd. In the mid-1940s the number of students reached 150. Its population was Muslim, and the village houses were built of adobe brick.
Agriculture was the main source of income. Toward the end of the Mandate, the village community cultivated grain, vegetables, and fruits, including 240 dunums of citrus. Agriculture was both rainfed and irrigated from deep (35 to 40 m) wells. Simsim was ringed by fruit trees and gardens, but most of its fruit trees were concentrated in the southwestern lands, which received the flood water from the wadis. In 1944/45 a total of 240 dunums was devoted to citrus and bananas and 12,086 dunums were allocated to cereals; 250 dunums were irrigated or used for orchards. The village included an archaeological mound known as al-Ras and was surrounded by three other archaeological sites, among them a Roman cemetery (known in modern times as Sha'fat al-Mughur) with rock-cut tombs.
In one of its northward thrusts, just before 15 May 1948, the Palmach's Negev Brigade captured the village and expelled its inhabitants. This was effected in the wake of the occupation of Burayr on 12–13 May, according to Israeli historian Benny Morris. Another source contradicts this account, however. The New York Times mentions that Simsim was occupied two months later, during the Ten Days between the two truces, shortly before 11 July. But the report is suspect because it states that Simsim was occupied along with a cluster of villages well to the north, along the al-Majdal-al-Latrun road. It seems unlikely that these widely-separated villages would have been seized at the same time.
The settlement of Gevar'am was established in 1942 on lands that traditionally belonged to the village. The settlement of Or ha-Ner was built in 1957 less than 1 km south of the village site, on the lands of Najd.
The village has been obliterated and can only be recognized from the cypress and sycamore trees that still remain. A pile of stones that may be the debris of a village building is visible. The site is fenced in and serves as a pasture. The lands in the vicinity are cultivated by Israeli farmers.