Discussions, post-mortems, analysis, inflated egos, and all that jazz.

the country you live in is as old as Ukraine

The Russian Federation is the successor to the USSR, having taken over its debts (up to $120 billion, according to various sources) and obligations under all treaties, as well as the burdens of the status of a nuclear superpower, so don't compare them.

Russia began with the Moscow state

The Moscow state is the direct heir to the entire patchwork of Orthodox principalities of ancient Rus', including Kyiv, from where the Patriarch of All Rus' moved to the forests (and at that time, statehood with all its nascent modern institutions was based precisely in the church).

Statehood is not a piece of land, nor is it the mythical "people" or "nation" - it is management and logistics. Moscow was located in a favorable area at the watershed of three river basins, from where both Eastern Europe, the south, and the east were controlled, plus it was further away from the Horde, which is why the new center of Rus' emerged here after the devastation of Kyiv.

the first mentions of Ukraine date back to the 12th century

- mentions as a territory, not as a state. In general, there were many Ukrainians; this term denoted something that was "at the edge," since there were no borders in the modern sense before, but rather there were only borderlands - either disputed territories or undeveloped ones.

I anticipate: "kraina" is a little different. Both words come from "krayati" - to cut the skin (most likely, the primary sound was "kr-r-r" - when you cut it with a knife).
Krai is an area where the "commodity part of the skin" of the state ends and the "scraps" begin.
Ukraina is an area on both sides of the edge, i.e., including both the area of civilization and undeveloped places.
The "kraina" common in Eastern Europe denotes the result of "cutting up" the land, i.e., establishing borders on all sides.