What do we know about it.
you (proverbial) suggest that eveyone is guilty so in the end nobody is gulity.
Anyways nobody wants some stupid apologies.
Yes?
here comes. It connected to Ortodox Eastern religion, after fall of the Byzantium Constantinople center of the religion was to be either in Kiev or Moscow, Greek clergy dominated there, after much infighing, the head man run off to Moscow given better terms, from there he claim to be in charge both Kiev and Moscow as a religious leader.
That claim give a leg to semi-legal claims for people and land to the Grand Duke of Moscow, that at this stage named himself Tsar of whole Russia i.e. all people and lands that are Ortodox no matter if they like it or not. (Some version of Ruski Mir).
Rus in Greek Ortodox clergy terminology was connected with the ortodox religion not with the people.
Hope it helps.
coz I know everything about the Polish Ukrainian relations
Libicki? Is that you? Get lost!