Brenhinedd y Saesson

Brenhinoedd y Saeson (English: The Kings of the English) is the medieval title of three Middle Welsh annalistic chronicles known from three 14th-century manuscripts (referred to as P, R, and S) recording events from 682 to the English conquest of Wales in 1282 (P was subsequently continued to 1332, S ultimately to 1461). The title Brenhinoedd y Saeson is found only in the rubric to the earlier of the two surviving manuscripts of version S: the other two texts are commonly known as Brut y Tywysogion, but this title is found only in manuscripts of the late 16th century and cannot be considered authentic.

The three versions of Brenhinoedd y Saeson are closely related to and are probably translations from a text or texts evidenced by those Cambro-Latin annalistic chronicles now known as Annales Cambriae.

P survives in a single medieval manuscript:
Aberystwyth, National Library of Wales, MS. Peniarth 20, written c.1330, probably at the Cistercian abbey of Valle Crucis (Llanegwestl). The scribe of this manuscript also wrote the earlier of the two manuscripts containing S.

R survives in four medieval manuscripts:

These all date from about 1350 to about 1400.

S survives in two medieval manuscripts:

P is datable 1286 – c.1330; R is datable 1307 – 1350; S is datable c. 1200 (probably 1282 or 1286) – 1300. The order of composition of the three versions remains to be determined.

...
Wikipedia