[egorfine]

How beautiful is this project exactly if it presents quite an inaccurate data?

I'm not talking about minute details.

For instance, lookup wikipedia for "Grand Duchy of Lithuania" and note the active years of that state in all its different phases. Then compare with what this map shows.

[perfunctory]

Could you give an example? Like a specific year when the map is not accurate?

[Freak_NL]

Lots of things are missing. The kingdom of Frisia (6th to 8th century CE) is completely absent.

[ivan4th]

Urartu is missing as well: https://en.wikipedia.org/wiki/Urartu