Countries in history with the most in common

I think Lithuania and Belarusia (as you call i want to call it more White Ruthenia). In XIII century lithuanian and white ruthenian lands almost all joined to Grand Duchy of Lithuania. Till end of XIV century to Grand Duchy were joined almost all ruthenian lands, but after 1569 Union with Poland big part of Ruthenia (almost all modern Ukraine) were joined to Poland. So to Grand duchy left again Lithuanian and white ruthenian (belarusian lands)..After 1795 thoose lands both were joined to Russian empire and was there still 1915 (now don't remember good did german occupied Belarusian lands in 1915?). At 1919 again.. thoose to countries were joined to Litbel SSR (as i understand Lithuania - Belarusia). But this country didn't exists, Lithuania won freedom and Belarus - no.

Finally both countries were joined to Soviet union.. and only after we, lithuanians, first from all SSRS declared independence on 1990 we are different countries

What about yours?

Without using any historical parameters, I think the two most common countries have been the U.S. and Canada.  There is almost no difference between them at all.

Yes, Canada has a French minority, but the US has a Spanish minority.

Australia and New Zealand

Britain and Ireland

Czech and Slovak Republics

India and Pakistan

Raider wrote:

"Do you know why White Ruthenia is white and Red Ruthenia is red?"

Once there existed a tradition to designate different sides of the  world by different colours; thus, "red" stands for South, "black" - for North, "blue" - for East and "white" - for West. >>> Red Ruthenia means Southern Ruthenia, White Ruthenia = Western Ruthenia.