In the 11th century the Counts of Savoy and Valromey settled in the region of Belley. In 1272, when Sibylle de Bâgé, sole heir, married Amadeus V, Count of Savoy, they added the Bresse to their domains, and – by the Treaties of Paris in 1355 – the territories of Dauphiné and Gex on the right bank of the Rhône. In the beginning of the 15th century almost the whole region of Ain was united under the house of Savoy. New monasteries were founded in the cities and churches were constructed or reshaped according to the Gothic style of architecture.