A TRACON Controller reported a non-tracked IFR target in their airspace below the MVA that an adjacent facility failed to handoff resulted in a CFTT event.

Narrative

Aircraft X was a primary only target flying through the airspace appeared level at 050. Issued the traffic to an Airbus that descending out of 080 for 060 landing ZZZ per our LOA (Letter Of Agreement) with ZZZ approach. I instructed the Airbus to stop at 070 to give some extra altitude to avoid a TCAS. I then realized that the primary only target was on a beacon code so I had handoff the code in the FDIO (Flight Data Input/Output). The flight plan showed IFR from ZZZ1 to ZZZ IFR 050 feet. That aircraft was now in a 047 MVA but the last 20 miles before that from ZZZ1 from ZZZ approach was 051;060;052 and then 051 again on the MVA. I was never given any info on the aircraft we never took radar on them and ZZZ never called to coordinate. I immediately reached out to the aircraft was then just checking on 6 south west of ZZZ. I asked if they had been cleared IFR from ZZZ approach and they said affirmative; so as they started approaching the 054 MVA I gave them a climb to meet the next MVA. It appeared they were not going to meet that MVA so we got a point out with the tower to turn them east bound keep them climbing and avoid any further altitude issues. During this time Handoff took a call from ZZZ and all the controller said was Aircraft X not sure what happened with him. I vectored the Aircraft X into the left downwind and sequenced him in without any further issues. Complete incompetence and straight disregard for rules and safety on ZZZ approach; they are very aware of our complex air space due to mountainous terrain. Controllers need to be well rested and in the correct state of mind to continue to work the ever changing and expanding aircraft volume and complexity. There is no reason we should be sitting on position thinking about when our next paycheck will come. Most families have enough personal issues and for the government to just not pay us for the work we are doing is egregious.