The use of 'ancestral land' as justification can be used by some to an extent but not others since it's used to batter other factors and can mask the ebb and flow of history in a region.
Re Crimea, if I remember the figures from the all Russian Empire census of 1897, apart from major cities such as Sevastopol which had an influx of Russians and others, the population was predominantly Tatar. And IIRC though the non Tatar population grew after the establishment of the USSR, the Tatars were still in the majority until after 1944.
As for Donetsk and the Donbas, and I appreciate it's a simplified snapshot, but prior to the time of Catherine the Great, about mid late 1700s IIRC, this was not part of Russia but the 'wild steppe' thinly populated with runaways from Little and Greater Russia but within the orbit of and squeezed between both Russia the Tatars and the Ottomans. After Catherine's push south to take over this area, and Crimea and what became the region around it and Odessa, in addition to Russian governors and rulers, those brought in to work and settle were a mixture of mostly Ruthenians and Romanians and also others who were the majority. The Russification increased after the establishment of the coal mines and accelerated post USSR.
I recall a few years ago a documentary item from a village in Donetsk (or probably Luhansk) some chap saying this is 'our land, not Ukrainian' and the woman villager standing next to him suddenly saying something along the lines of 'what? I've never seen you here before'.
In a Youtube clip that popped up for me about the differences between the Ukrainian and Russian languages, the Ukrainian though Russian speaking lady Youtuber was explaining that in east Ukraine Russian is spoken in the cities and towns, whilst in the surrounding countryside it's Ukrainian. Without checking the stats myself I don't know how true the extent of this is but I give it credence.
The Black Sea steppes had been part of the Ottoman Empire, and was sparely inhabited by nomadic Turkic tribes. Crimea was an exception, as they had been an outpost of trade at least as far back as the classical Greeks and had a quite varied population.
The Russian and Ottoman Empires collided for a variety of reasons, but one of the things pushing the Russians to move against the Turkic tribes in both the Black Sea area and Central Asia was that part of the economy of the Turkic tribes was based on raiding Russia for loot, particularly slaves. The plight of Christian slaves in the hands of Muslim slave masters and plantation owners was a political issue in Russia, and this alone if nothing else would probably have pushed them to "do something" about it.
The Cossacks were Russians who had lived on the frontier for a long time. They acted as a form of border defence for the Russians and so were given special privileges in return for their services.
When the Russians decided to deal with the Ottomans in the north Black Sea area once and for all, their biggest problem was logistical. The area was arid, had little in the way of roads, and was short of water in summer.
When they did conquer the region, part of the peace agreement included the Ottomans resettling most of the Turkic tribes elsewhere in the Ottoman Empire. Some of them ended up in places such as Syria.
Some however remained. These by the way included a group in Ukraine who tried to form their own independent country when Ukraine declared independence, but were crushed by the Ukrainian army. This sort of thing was common when the Soviet Union collapsed and the new republics who declared themselves independent decided that independence was only for those ethnic groups big enough to make it stick.
Going back to a few hundred years again, Crimea became part of Russia while the "mainland" territories became "Ukraine". What is now western Ukraine was part of the Austro-Hungarian Empire and its successor states (e.g. Poland), and did not become part of Soviet Ukraine until the end of WWII. In the 19th century other countries considered the people of what we call western and eastern Ukraine to be distinctly different ethnicities.
In Russian Ukraine settlers moved into the newly available lands much as Americans moved into their own "west", and at relatively similar times. In both cases I suspect that technological developments such as railways and steel ploughs played as big a role as politics did.
When we talk about languages and ethnicity, we need to take into account that such things are in many cases and to a large extent relatively modern creations. Late Russian Empire and early Soviet government plans for economic development required educating the masses using standardised textbooks printed in large numbers, and that in turn required standardising the language.
This process also took place in the rest of Europe. For example, before the creation of "Italy" there wasn't an "Italian" language in the modern sense. Instead there were local dialects, many of which were not mutually intelligible. If someone from Sicily travelled to the far north of Italy and spoke to a native there each in their own dialect, they would not be able to understand one another. The differences between Italian dialects can be at least as great as the difference between Italian and say Spanish. They were effectively different languages. The Italian state solved this problem by declaring the dialect of Florence to be the "official" version of the Italian language, and all school pupils were required to learn it and be educated in it even if they continued to use their own dialect at home.
In a similar process the Russian Empire and the Soviet Union standardised languages and made them official as a necessary process in the economic development of the country.
However, every province of the Russian Empire and republic of the Soviet Union was multi-ethnic in nature. Every minority had within their territories their own minorities in turn. The Russian Empire and the Soviet Union tried to accommodate this out of necessity.
However, after the collapse of the Soviet Union many of the newly independent states sought to create a new national identity for themselves both to try to prevent themselves from splitting, and also to placate the nationalist activists who had driven the process of independence in the first place.
The most ardently nationalistic and anti-Russian parts of Ukraine are the parts which had never been part of the Russian Empire or the Soviet Union until the post-WWII annexations. One wonders how things might have turned out if the Soviets had refrained from that annexation and left the Poles with a Ukrainian minority headache and whether traditionally Russian/Soviet Ukraine would have remained more closely aligned with post Soviet Russia.
Macron has certainly intimated that.
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www.reuters.com
eeas.europa.eu
