The land ruled by King Melwas, Guinevere’s abductor in Caradoc of Llancarfan’s The Life of St. Gildas.
As Glastonbury is said to be nearby, the Summer Region is probably Somerset. It may have some relation to the Summer Country of Culhwch and Olwen.
Source
Vita Gildae | Caradoc of Llancarfan, c. 1130
