History of Portugal (1640–1777) put to the test in 1762 when Spain invaded aided by France, during the Seven Years' War. Britain invoked its alliance with Portugal and sent troops. Several months later, the conflict was settled with comparatively little fighting. In 1777, Spain and Portugal signed the Treaty of San Ildefonso, which mainly resolved a number of border disputes between their South American colonies. During the Age of Enlightenment, Portugal was considered one of Europe's unenlightened backwaters; it was a country of three million with 200,000 people in 538 monasteries in 1750. Melo seems to have been deeply embarrassed by Portugal's much lamented
Japan–Russia border into the Soviet Union in 1945. Russia treats the islands as an integral part of the country. There are no border crossing points on the Russian-Japanese border, as it is a purely maritime boundary. During the existence of the land border in Sakhalin (1905-1945), it was crossed by one road. Soviet–Japanese border conflicts Japan–Russia border The Japan–Russia border is the "de facto" maritime boundary that separates the territorial waters of the two countries. According to the Russia border agency, the border's length is 194.3 km. The two countries do not share a terrestrial border, although in 1905-1945 the Russian Empire,