During the last Ice Age, a thick layer of ice covered much of Sweden. By 6,000 BC, when that ice finally retreated (or melted) across the southern areas, it left in its wake a jagged coastline with many islands, and innumerable lakes, rivers and streams.
Subsequently, the exposed lands turned green and fertile, wildlife returned, and it is thought that the first settlers arrived here from Denmark and Norway. Archaeological evidence indicates that groups of early man lived and farmed in southern Sweden throughout the Neolithic Stone Age and Bronze Age.
Over time, widely scattered tribes formed; chiefdoms then developed - communities of people led by an all powerful chief. Small kingdoms followed including the Suiones and Geats, and in the far north, the Sami people (or Laplanders) inhabited vast areas of land.
Sweden's Viking Age began in the late 800's AD, and unlike the Danish and Norwegian Vikings, the Swedes traveled south and east. They raided Finland and other Baltic Sea lands. They trekked across much of western Russia, and these rugged adventurers navigated rivers all the way to Constantinople, better known today as Istanbul, Turkey.
Viking trade brought wealth to this land, as well as Christianity, introduced by St. Ansgar around 829. Regardless, paganism (or folk religions) remained in the forefront well into the 12th century. During the High Middle Ages an assortment of (competing) Nordic kingdoms sought more power and more land, and a few Swedish monarchs began to extend their kingdoms into Finland and beyond.
Regional squabbles were silenced by the 1350's as the Black Plague, the planet's most devastating pandemic, killed millions across Europe and much of Sweden's population, especially in the south.
At the very end of the 14th century, Queen Margaret I of Denmark influenced a union of sorts between Sweden, Norway, and Denmark. That so-called Kalmar Union of mostly self-serving dynasties was marred by Denmark's military aggression, especially against Swedish nobility. National pride took hold, and on the 6th of June 1523, Gustav Vasa was crowned King of Sweden, and the country's modern history began.
After a dispute with the Pope in Rome over the expulsion of a Catholic Archbishop, King Gustav I rejected Catholicism and led Sweden into Lutheranism and the Protestant Reformation. Though Gustav Vasa's autocratic reign is reviewed by some as power-hungry and ruthless, he liberated his people and is widely revered today as the "Father of the Nation".
Beginning in the mid-1700's, Sweden was an influential power in Europe, and the country reached out to establish colonies in Africa and the Americas. Kings with great armies and the resulting wars came and went, and at the dawn of the 19th century, Sweden did not have enough resources to maintain its territories outside Scandinavia, and most of them were lost.