Ukrainians (Ukrainian: ukrayintsi, ukrayintsi, [ukra'jinjtsji]) are an East Slavic ethnic group native to Ukraine, which is by total population the sixth-largest nation in Europe. The Constitution of Ukraine applies the term 'Ukrainians' to all its citizens. Also among historical names of the people of Ukraine, Rusyns (Ruthenians), Cossacks, etc. can be found. According to most dictionary definitions, a descriptive name for the "inhabitants of Ukraine" is Ukrainian or Ukrainian people.
Early history
The ethnonym Ukrainians became widely accepted only in the 20th century after their territory obtained distinctive statehood in 1917. From the 14th to the 16th centuries, the Western portions of the European part of what is now known as Russia, the territories of northern Ukraine and Belarus (Western Rus') were largely known as Rus', continuing the tradition of Kievan Rus'. People of these territories were usually called Rus or Rusyns (known as Ruthenians in Western and Central Europe). The Ukrainian language appeared in the 14th - 16th centuries (with some prototypical features already evident in the 11th century), but at that time, it was mostly known as Ruthenian, like its brothers. In the 16th - 17th centuries, with the establishment of the Zaporizhian Sich, the notion of Ukraine as a separate country with a separate ethnic identity came into being. However, the ethnonym Ukrainians and the linguonym Ukrainian were used only occasionally, and the people of Ukraine usually continued to call themselves and their language Ruthenian. After the decline of the Zaporizhian Sich and the establishment of Imperial Russian hegemony in Ukraine, Ukrainians became more widely known by the Russian regional name, Little Russians (Malorossy), with the majority of Ukrainian elites espousing Little Russian identity. This official name (usually regarded now as colonial and humiliating) did not spread widely among the peasantry which constituted the majority of the population. Ukrainian peasants still referred to their country as Ukraine (a name associated with the Zaporizhian Sich, with the Hetmanate and with their struggle against Poles, Russians, Turks and Crimean Tatars) and to themselves and their language as Ruthenians/Ruthenian. With the publication of Ivan Kotliarevsky's Eneyida (Aeneid) in 1798, which established the modern Ukrainian language, and with the subsequent Romantic revival of national traditions and culture, the ethnonym Ukrainians and the notion of a Ukrainian language came into more prominence at the beginning of the 19th century and gradually replaced the words "Rusyns" and "Ruthenian(s)". In areas outside the control of the Russian/Soviet state until the mid-20th century (Western Ukraine), Ukrainians were known by their pre-existing names for much longer. The appellation Ukrainians initially came into common usage in Central Ukraine and did not take hold in Galicia and Bukovyna until the latter part of the 19th century, in Transcarpathia until the 1930s, and in the Presov Region until the late 1940s.  The modern name ukrayintsi (Ukrainians) derives from Ukrayina (Ukraine), a name first documented in 1187. Several scientific theories attempt to explain the etymology of the term.  According to the traditional theory (especially predominant in Russia), it derives from the Proto-Slavic root *kraj-, which has two meanings, one meaning the homeland as in "nash rodnoi kraj" (our homeland), and the other "edge, border", and originally had the sense of "periphery", "borderland" or "frontier region" etc.  According to some new alternative Ukrainian historians such as Hryhoriy Pivtorak, Vitaly Sklyarenko and other scholars, translate the term "u-kraine" as "in-land", "home-land" or "our-country". The name in this context derives from the word "u-kraina" in the sense of "domestic region", "domestic land" or "country" (inside the country).  In the last few centuries the population of Ukraine experienced periods of Polonization and Russification, but preserved a common culture and a sense of common identity.  Most ethnic Ukrainians live in Ukraine, where they make up over three-quarters of the population. The largest population of ethnic Ukrainians outside of Ukraine lives in Russia where about 1.9 million Russian citizens consider themselves ethnic Ukrainians, while millions of others (primarily in southern Russia and Siberia) have some Ukrainian ancestry. The inhabitants of the Kuban, for example, have vacillated among three identities: Ukrainian, Russian (an identity supported by the Soviet regime), and "Cossack". Approximately 800,000 people of Ukrainian ancestry live in the Russian Far East in an area known historically as "Green Ukraine".  According to some previous assumptions, an estimated number of almost 2.4 million people of Ukrainian origin live in North America (1,359,655 in Canada and 1,028,492 in the United States). Large numbers of Ukrainians live in Brazil (600,000), Kazakhstan (338,022), Moldova (325,235), Argentina (305,000), Germany (272,000), Italy (234,354), Belarus (225,734), Uzbekistan (124,602), the Czech Republic (110,245), Spain (90,530-100,000) and Romania (51,703-200,000). There are also large Ukrainian communities in such countries as Latvia, Portugal, France, Australia, Paraguay, the UK, Israel, Slovakia, Kyrgyzstan, Austria, Uruguay and the former Yugoslavia. Generally, the Ukrainian diaspora is present in more than one hundred and twenty countries of the world.  The number of Ukrainians in Poland amounted to some 51,000 people in 2011 (according to Polish Census). Since 2014, the country has experienced a large increase in immigration from Ukraine. More recent data put the number of Ukrainian workers at 1.2 - 1.3 million in 2016.  In the last decades of the 19th century, many Ukrainians were forced by the Tsarist autocracy to move to the Asian regions of Russia, while many of their counterpart Slavs under Austro-Hungarian rule emigrated to the New World seeking work and better economic opportunities. Today, large ethnic Ukrainian minorities reside in Russia, Canada, the United States, Brazil, Kazakhstan, Italy and Argentina. According to some sources, around 20 million people outside Ukraine identify as having Ukrainian ethnicity, however the official data of the respective countries calculated together doesn't show more than 10 million. Ukrainians have one of the largest diasporas in the world.  Ukraine has had a very turbulent history, a fact explained by its geographical position. In the 9th century the Varangians from Scandinavia conquered the proto-Slavic tribes on the territory of today's Ukraine, Belarus, and western Russia and laid the groundwork for the Kievan Rus' state. The ancestors of the Ukrainian nation such as Polianians had an important role in the development and culturalization of Kievan Rus' state. The internecine wars between Rus' princes, which began after the death of Yaroslav the Wise, led to the political fragmentation of the state into a number of principalities. The quarreling between the princes left Kievan Rus' vulnerable to foreign attacks, and the invasion of the Mongols in 1236. and 1240. finally destroyed the state. Another important state in the history of the Ukrainians is Kingdom of Galicia-Volhynia (1199-1349).  The third important state for Ukrainians is Cossack Hetmanate. The Cossacks of Zaporizhia since the late 15th century controlled the lower bends of the river Dnieper, between Russia, Poland and the Tatars of Crimea, with the fortified capital, Zaporizhian Sich. Hetman Bohdan Khmelnytsky is one of the most celebrated and at the same time most controversial political figures in Ukraine's early-modern history. A brilliant military leader, his greatest achievement in the process of national revolution was the formation of the Cossack Hetmanate state of the Zaporozhian Host (1648-1782). The period of the Ruin in the late 17th century in the history of Ukraine is characterized by the disintegration of Ukrainian statehood and general decline. During the Ruin Ukraine became divided along the Dnieper River into Left-Bank Ukraine and Right-Bank Ukraine, and the two halves became hostile to each other. Ukrainian leaders during the period are considered to have been largely opportunists and men of little vision who could not muster broad popular support for their policies. There were roughly 4 million Ukrainians at the end of the 17th century.  At the final stages of the First World War, a powerful struggle for an independent Ukrainian state developed in the central Ukrainian territories, which, until 1917, were part of the Russian Empire. The newly established Ukrainian government, the Central Rada, headed by Mykhailo Hrushevsky, issued four universals, the Fourth of which, dated 22 January 1918, declared the independence and sovereignty of the Ukrainian National Republic (UNR) on 25 January 1918. The session of the Central Rada on 29 April 1918 ratified the Constitution of the UNR and elected Hrushevsky president.

Q: what was the early history like?
A: The ethnonym Ukrainians became widely accepted only in the 20th century after their territory obtained distinctive statehood in 1917.

Q: how did it obtain distinctive statehood?
A: unknown

Q: what else did they do in their early history?
A: The Ukrainian language appeared in the 14th - 16th centuries (with some prototypical features already evident in the 11th century),
did it become widely used?
unknown
unknown