Respuesta :

The answer is: the moscow grand princes (tsar) were in charge to title and granting power to the boyars

Boyar is a noble Slav landowners, although it is used mainly in the Russian, Serbian, Bulgarian and Romanian (including Moldova). In Russia. They would occupy high posts in the armed forces, they would advise the prince in importants matters. The country would be ruled by the tsar with the help of the boyars, due to this power granted by them (princes).

When Ivan IV came to power in 1547, much more of the boyar's independent political power became obsolete. The independence and autonomy experienced by the princes of the regions in Russia was abolished under Ivan IV by the end of the sixteenth century, making them “the prince’s sons”, or just simple boyars serving the Grand Prince.