“Ukraine” never even existed outside of a Soviet politburo scheme to create it in 1920s. There is no Ukraine nation. It’s a cesspool of Nazi Banderite Russophobes that Schwab-Soros-US/UK Stasi operatives are using to create a dumpster for weapons sales and human lives.
Ukraine was seen as a separate territory with a distinct population since at least the 17th century.
The name should give you a hint “u kraina” on the border in polski. It was the land between Poland, Muscowy and the Ottomans.
The first Ukrainian state was the Kievan Rus’. The Rus’ part from the name might be misleading as it could suggest that was a Russian state. Rus’ was actually the name of the Vikings who were the overlords of the local Slavs (Ukrainians, Belarusians, Russians). Just like in the case of the Germanic Frank overlords, who passed their name onto the French, the Russians got their modern name from those Germanic overlords, the Rus’.
Kievan Rus’ lasted for about 300 years then succumbed to internal strife and the Mongol invasion.
The Ukrainians had another short-lived state as Zaporozhan Cossacks in the 17th century, after successfully rebelling against the Polish-Lithuanian Commonwealth. However they had to seek the protection of the Russians and ended up annexed by the early 18th century.
So when Ukraine became independent again after the signing of the Treaty of Brest-Litovsk, that was the 3rd attempt at statehood. From 1991 until now we have the 4th Ukrainian state.
Russian trolls love to claim Ukraine never existed before Brest-Litovsk taking advantage of the fact most of the people never heard of the Kievan Rus’ (and if they did, they would believe the Rus’ were Russians).
Ukrainian nationalism was born initially out of the conflict with the Poles and was later amplified by the Russian state systematic attempts at eradicating the Ukrainian language. Those efforts begun in the 17th century and lasted until 1917.
The 1918 Brest-Litovsk treaty signed by Germany and Russia included Russia’s recognition of several independent countries, including Poland, Finland, Ukraine, Latvia, Estonia, and Lithuania - all former parts of the Russian Empire. A few years later, Russia subverted and attacked Ukraine, using methods similar to those used in 2014-15 (trying to blow up internal conflicts into a civil war, sending regular and irregular troops, forming puppet governments). This was successful in that Ukraine lost the short-lived independence and became a part of the USSR. Russia also attacked Poland, but was beaten at the Wisła.