It consisted of the country bounded by the rivers Loughor, Amman, Twrch and Tawe. Its capital and chief castle was Swansea, and it extended westward to the end of the Gower peninsula and northward to Ystalyfera and Gwaun-Cae-Gurwen. Soon after the Norman invasion the southern part was colonised by English speakers, and the lordship was formally divided into Welsh Gower and English Gower. The parish of Betws was detached from the lordship in the 13th century.
In the first Act of Union (1535), it was transferred, along with the Lordship of Kilvey (roughly, the parish of Llansamlet on the east bank of the Tawe), to the historic county of Glamorgan, when the north-eastern part became the Hundred of Llangyfelach and the south-western part became the Hundred of Swansea. However, the district remained part of the Diocese of St David's, until the Diocese of Swansea and Brecon was formed in 1923.
The rights of Marcher lords were formally abolished by the Act of Union, but considerable powers were still exercised de facto in Gower, and the claimed rights and privileges of the Lord (then a Duke of Beaufort) were described in detail in Gabriel Powell's Survey of Gower in 1746.
The name of the area has continued in use since 1885 in the name of the parliamentary constituency which consists of all the lordship other than Swansea city, but today the name Gower is commonly incorrectly applied only to the south-western, peninsular part of the district (see Gower peninsula).
The medieval division between English and Welsh-speaking areas continues today, the peninsula and the coastal part of Swansea city being English-speaking, while Welsh is spoken further north, and places such as Ystalyfera and Gwaun-Cae-Gurwen remain bastions of the Welsh language. The boundary shown on the map is that of D T Williams (1931). It had changed little in several centuries.