The fourth phase of exploration in what is now Canada consisted of Frobisher's three voyages (1576, 1577 and 1578) and the two voyages of Davis (1586 and 1587) made in search of a northwest passage to Asia. These voyages represented the initial penetration of the Arctic. The map also shows the extent of territory known to Europeans in the period 1497 to 1650; and the navigation of all exploration routes during the period of maritime exploration between 1497 and 1599. The historical names found on the map are derived from contemporaneous maps and written documents of the period.