History of Ukraine
WARNING: Ukraine is politically unstable, please read this travel warning before going!
Ukraine's settled history begins in the 7th century BC when the Greeks established a couple settlements along the Black Sea coast. Over a thousand years later the Slavs were forming a more and more distinct ethnicity and in 879 AD the Rus unified in Kyiv and over the next couple hundred years continued to grow until 989, when they adopted Eastern Orthodox Christianity.
After the death of their ruler, Yaroslav, in 1054, the empire fell into small individual states so when the Mongols arrived in 1240, they easily took the entire region. Their rule continued until the 1400s when the Golden Horde (the Mongols) collapsed.
During much of this same period, the Carpathian Mountains of present-day Ukraine fell under Polish and western Slavic rule. Being in the mountains, some of these regions even withstood Mongol takeover. This rule by Poland created better communication with the west and a fairly distinct culture from that in the east and south of modern-day Ukraine.
In the mid-1400s, the Golden Horde was collapsing and each individual region began to rule itself, some by Slavs, some by the Mongol descendants, the Tatars, and some by the Cossacks, who typically consisted of a mix of ethnicities from the surrounding areas. Over time the Cossacks formed a more distinctly defined identity, which differentiated them from the Turks and Poles through religion and from the western Ukrainians by lifestyle. In 1654 the Cossacks tried to free themselves from Polish rule, but their protests only resulted in placing themselves under Russian rule, which was a group that developed from the original Kyivian Rus, but moved more northward under Mongol rule.