The origin of the Castilla y León regional Parliament, as much the kingdom of Castilla as the kingdom of León , goes back to the XII century, which make it one of Europe's oldest representative institutions. The first written reference is from the year 1188, with the meeting call of Alfonso IX from León. At that meeting attend representatives from cities and towns, the nobility and clergy.
In Castilla, Alfonso VIII will probably make the first call of the Parliament in the year 1187, taking place in San Esteban de Gormaz and where attend representatives from fifty cities.
All those meetings and the subsequent ones are the precedent of the current democratic Parliament that was created due to the Castilla y León Statue of Autonomy and whose first session dates from 1983.
Among all the functions of the current Parliament, we must highlight its legislating function, in the scope of the Statute of Autonomy, and the function to monitor the regional government and its President. But together with these functions, this institution is also in charge of the budget approval, of the election of the regional government President and the autonomic senators and to impose and collect taxes.
Regarding its composition, the Parliament is composed of deputies chosen by universal suffrage with a minimum number of three deputies for every province, another one for every 45,000 inhabitants or fraction over 22,5000, whose term of office last, usually, four years.