The Book of Leinster (TCD MS 1339, formerly H.2.18) is the earliest manuscript written entirely in Irish in Trinity College Library and is one of the most important manuscripts of the Middle Irish period. The manuscript, formerly known as Lebor na Nuachongbála, is named after a monastic site in Co. Laois. Of the number of scribes who worked on it only one is known by name: Aed mac meic Crimthaind, the abbot of the monastery of Tír-Dá-Glas on the Shannon, Co. Tipperary. It is an anthology of Irish prose, verse and genealogy containing an important selection of medieval Irish texts. They include the Lebhor Gabála (The Book of Invasions), a narrative on the origin of the Irish, the corpus of topographical lore Dindshenchas Érenn (tradition or lore of places within Ireland) and the heroic epic, Táin Bó Cúailnge (The Cattle Raid of Cooley). The manuscript was acquired by the Welsh antiquary Edward Lhuyd (1660-1709) and was presented to Trinity College Library as part of a collection of 43 Irish manuscripts in 1786 by Sir John Sebright (d.1794).