Complex sentence: Pierre Desceliers, allowed the realization of many maps, and based at the same time, the portulans of the Portuguese sailors had the most recent knowledge obtained by the Dieppois sailors in their exploration of Canada.
Split into simpler sentences: Pierre Desceliers, allowed the realization of many maps. At the same time, the Portolan maps of the Portuguese sailors had the most recent knowledge obtained by the Dieppois sailors in their exploration of Canada.