and political environment provided by the Aberffraw administration allowed for the natural development of Welsh culture, particularly in literature, law, and religion. Tradition originating from The History of Gruffydd ap Cynan attributes Gruffydd I as reforming the orders of bards and musicians; Welsh literature demonstrated "vigor and a sense of commitment" as new ideas reached Wales, even in "the wake of the invaders", according to historian John Davies. Contacts with continental Europe "sharpened Welsh pride", wrote Davies in his History of Wales. Economy and trade The increase in the Welsh population, especially in the lands of the principality, allowed for a greater diversification of the economy. The Meirionnydd tax rolls give evidence to the thirty-seven various professions present in Meirionnydd directly before the conquest. Of these professions, there were eight goldsmiths, four bards (poets) by trade, 26 shoemakers, a doctor in Cynwyd and a hotel keeper in Maentwrog, and 28 priests; two of whom were university graduates. Also present were a significant number of fishermen, administrators, professional men and craftsmen. With the average temperature of Wales a degree or two higher than it is today, more Welsh lands were arable for agriculture, "a crucial bonus for a country like Wales," wrote the historian John Davies. Of significant importance for the principality included more developed trade routes, which allowed for the introduction of new energy sources such as the windmill, the fulling mill and the horse collar (which doubled the efficiency of horse-power). The principality traded cattle, skins, cheese, timber, horses, wax, dogs, hawks, and fleeces, but also flannel (with the growth of fulling mills). Flannel was second only to cattle among the principality's exports. In exchange, the principality imported salt, wine, wheat, and other luxuries from London and Paris. But most importantly for the defence of the principality, iron and specialised weaponry were also imported. Welsh dependence on foreign imports was a tool that England used to wear down the principality during times of conflict between the two countries. 1284 to 1543: annexed to the English crown Establishment and governance Between 1277 and 1283, Edward I of England conquered the territories of Llywelyn ap Gruffudd and the other last remaining native Welsh princes. The governance and constitutional position of the principality after its conquest was set out in the Statute of Rhuddlan of 1284. In the words of the Statute, the principality was "annexed and united" to the English crown.