I would like to clarify some local moments as far I was born in Soviet Union and have Ukrainian, Russian and Polish roots.
Ukraine is different. It was very rich in super prolific black soils many years ago, but it means nothing as for origin of black or any other tomato type or color!
More to say they have been loosing many of these wonderful soils since World War II when so many wagons with chernozem has been taken to Germany by fashists.
Back to Black Krim and the Crimean Penninsula. It has been gifted to Ukraine by native Ukrainian head of Communist Party of USSR Nikita Khrushchev in 1954 after so many years being part of Russian Empire since 1783 when Russians won it during Russian-Turkey (Russian Empire-Ottoman Empire) war.
Krim is a great place as for nature, flora or fauna, but you can't say it for sure there can be a birth place of black tomatoes.
But there are so many black tomato varieties came from Russia, including Black from Tula. Tula is an old Russian city about 200 km away from Moscow. It is famous of its traditional Russian gingerbread "pryanik", old traditional Samovar - a heated metal container traditionally used to heat and boil water in Russia for tea. Marina Danilenko from Moscow has sent its seeds to USA.
I've been to Tula city for 4 times for business in 2009-2012 and have no idea it is a motherland of black tomatoes. But they have a lot of traditional Russian black varieties at the local farmer's market. There was Black Prince everythere, because it is the most popular black tomato variety in Russia and CIS.
So I can't say for sure where are they came from (mutation or breeding or a gift from space aliens
), but we know and really love these Russian black tomato varieties:
Black Krim, Black from Tula, Chyornyi Prince (=Black Prince), Yaponskiy Tryufel Chyornyi (=Japanese Black Trifele) from Biotechnika seed company,St.Peterburg; Chyornyi Slon (=Black Elephant) from Moscow seed company Gisok; Chyornyi Mavr (=Black Mavr), Paul Robeson, Indira Gandhi, Kazachka, Chyornyi Baron (=Black Baron), Chernomor (=Black Sea Man) from VNIISOK, Black Russian, Dikovinka and many others...