Now republished with minor corrections, this volume provides the first comprehensive collection of charters, letters and other documents issued by native rulers of Wales from the early twelfth century to the Edwardian conquest of 1282–3 that extinguished independent rule. It thereby makes more accessible than ever before a key body of source material for the study of medieval Wales during ‘the age of the princes’ – an era of struggles for power by native rulers both among themselves and with Marcher lords and the English crown. The edition contains 618 documents, of which 444 survive as texts, while the remaining 174 are known only from mentions in other sources. The texts, almost all in Latin, are edited to modern scholarly standards and provided with full English summaries as well as notes on individual points of detail such as persons and places mentioned. Coverage is intentionally broad. The term ‘ruler’ has been applied to members not only of the dominant dynasties of Deheubarth, Powys and, above all, Gwynedd but also of minor dynasties such as those of Arwystli or Senghennydd; and, in a world where political power was often contested and fragmented, to individuals within each dynasty who exercised some measure of authority, however limited geographically or temporally. Likewise, the edition includes all known documents issued as expressions of a ruler’s will, including petitions and records of judgements as well as charters, letters patent and correspondence with other rulers, notably kings of England but also kings of France, popes and other churchmen. In addition, agreements with the English crown and other third parties are published irrespective of whether they survive in ratifications issued by the Welsh ruler concerned.