	Around 1490, the combined population of Poland and Lithuania, in a personal union (the Polish–Lithuanian union) since the Union of Krewo a century before, is estimated at about 8 million. An estimate for 1493 gives the combined population of Poland and Lithuania at 7.5 million (including 3.9 million in the Kingdom of Poland), breaking them down by ethnicity at 3.25 million Poles, 3.75 million Ruthenians and 0.5 million Lithuanians. The Ruthenians composed most of the population of the Grand Duchy of Lithuania: this is the reason that the late GDL is often called a Slavic country, alongside Poland, Russia etc. In time, the adjective "Lithuanian" came to denote a Slav of the Grand Duchy. 