According to the Palestinian Central Bureau of Statistics, the town had a population of 16,383 inhabitants in the 2007 census. The population is formed mainly of a number of families such as Frehat, Khamaysa, Samudi, Hushiya, Abu al-Hija, Samara 'Abahra, Zaid, Jaradat, Sharqieh and Nawahda that sourced many inspirational figures such as Ayham Frehat and Ibrahim Frehat .
Yamun, like the rest of Palestine, was incorporated into the Ottoman Empire in 1517, and in the census of 1596, the village appeared as “Yamoun”, located in the nahiya of Sara in the liwa of Lajjun. It had a population of 28 households, all Muslim. They paid a fixed tax rate of 25% on agricultural products, including wheat, barley, summer crops, olive trees, goats and beehives, in addition to occasional revenues; a total of 15,000 akçe. Potsherds from the Ottoman era have also been found here.
In 1882 the PEF's Survey of Western Palestine described it as “A large village, with olives round it, standing on high ground, with a well on the east. This appears to be the 'Janna of the Onomasticon,’ 3 miles south of Legio; does not exactly agree, being 7 English miles."
In the 1945 statistics the population was 2,520; all Muslims, with 20,361 dunams of land, according to an official land and population survey. 6,036 dunams were used for plantations and irrigable land, 11,121 dunams for cereals, while a total of 58 dunams were built-up, urban land.
On October 29, 2008, Muhammad 'Abahra, a farmer in the town was killed by the IDF. 'Abahra had a shotgun in his possession leading the IDF to believe he would fire at them. 'Abahra's son, however, alleged, that his father was guarding his sheep from suspected thieves.