Jubilees 8:29
28 And it extends to the region of the river Tina in a north-easterly direction until it approaches the boundary of its waters towards the mountain Rafa, and it turns round towards the north. 29 This is the land which came forth for Japheth and his sons as the portion of his inheritance which he should possess for himself and his sons, for their generations for ever; five great islands, and a great land in the north. 30 But it is cold, and the land of Ham is hot, and the land of Shem is neither hot nor cold, but it is of blended cold and heat.
1 Enoch 77:8
6 And these two come from the north to the sea and pour their waters into the Erythraean Sea in the east. 7 And the remaining four come forth on the side of the north to their own sea, 〈two of them〉 to the Erythraean Sea, and two into the Great Sea and discharge themselves there [and some say: into the desert]. 8 Seven great islands I saw in the sea and in the mainland: two in the mainland and five in the Great Sea.
Notes and References
"... From here the border again reaches familiar territory, going “to the edge of the Tina River toward the northeast until it reaches the banks of its waters toward the mountain range of Rafa. It goes around the north” (8:28). The next verse adds that Japheth’s eternal inheritance includes “five large islands and a large land in the north.” Four great islands in the Great Sea are also mentioned as part of Japheth’s son Tiras’ allotment in Jubilees 9:13. Since Shem has already been allotted the “islands of Kaftur”, we may deduce that these four are likely Crete, Sicily, Sardinia and Corsica. Based on a reference to “the islands and the shores of the islands” in the description of Madai’s portion (9:9), Hölscher and Alexander have suggested that the fifth great island of 8:28 is Britain, or the British Isles more generally. These islands were indeed known to the Ionians, making this identification plausible. (Charles, in The Book of Jubilees, p. 75, also noted the reference to islands in 1 Enoch 77:8) ..."
Machiela, Daniel A. The Genesis Apocryphon (1Q20): A Reevaluation of Its Text, Interpretive Character, and Relationship to the Book of Jubilees (pp. 243-244) University of Notre Dame, 2007