The ruins of Thaj can be seen about 80 km west of Al-Jubail. It is a small village situated beside a dry lakebed. The archaeological excavations undertaken by the Danish Mission in 1967 and those carried out by the Saudi Deputy Ministry of Antiquities in 1985 revealed Thaj as a complete buried city surrounded by a strong wall.

Much of the wall is damaged, but one section of about 900 meters is in good condition. Several mounds, walls, housing foundations, pottery shards, glass, necklaces and earrings, decorative objects, clay pots and figurines have been recovered from the site. It is possible that Thaj was established during the Greek Seleucid period, possibly around early third-century BCE.