Reported perfective is used for events or actions completed in the past,
and expresses that the knowledge of the fact is the result of the speaker having been told of it,
very often indirectly, by hearsay. That knowledge is in general deemed as dubious.
Other possibilities are that the knowledge is the result of direct narration (but then also seen as dubious), or even of dreams.
The knowledge is very often the result of indirect hearsay:
Bir ovchi ormonda qor odamni ko'rgan emish.
It is said that a hunter has seen a yeti.
Or it can be the result of a direct quotation, the content of which being not confirmed at least:
Eshitishimcha, bir qancha yigit Moskvaga o'qishga ketgan emish.
I've heard that some youths have gone to study in Moscow.
The knowledge is even more dubious when its topic is the speaker himself:
Bir qiz aytdi, men uylangan emishman.
A girl said such a thing, as if I got married.
The event or action may still have current relevance (perfect value, or experience):
Siz erga tekkan emishsiz.
I've been told you got married.
U Amerikaga ketganmish.
Some say he has left for America.
Sen Afrikada bo'lgan emishsan.
I've been told you have been in Africa.