A Center Controller reported they accepted a handoff of an aircraft which became NORDO and flew below the Minimum IFR Altitude.

Narrative

I was working DXX; PXX had just called me; in regards to a block they had requested being canceled; with an associated point out on an aircraft that had canceled IFR. After some time; the Data block was still up and showing an error on the EDST (En route Decision Support Control); this is unrelated to the incident; however it's what my mind was on when calling [ZZZ1 Center] back to clean up the situation. After determining with [ZZZ1 Center] that they had indeed terminated the aircraft; and Remove Stripped it; but it was still up in our system for some undetermined error; PXX decided to also include a non-radar hand off that was still a bit far out; since they already had me on the line.At the time; there was still roughly 10-20min before the low and slow aircraft entered my airspace; and their altitude was fine for another 10-20min entering my airspace. I approved the non-radar hand off; and while on the line with them; I recalled that our radios are notoriously bad in that area; and gave them a lost comes 70miles South East of ZZZ; to allow the aircraft to know that communication would be difficult.In retrospect knowing that radio's are an issue I should have un-abled the altitude immediately. However that distance (70miles SE ZZZ) is just a common point where comms are guaranteed and clear; however we can always reach aircraft earlier; though it can be spotty and hard to hear; and always in the event of something more imminent through a relay.However; I probably was not clear; that this was an 'in-the-event' of lost comms; and somewhere between me and [ZZZ1 Center] to the pilot; it seems the pilot was not even monitoring our frequency until 70miles SE ZZZ. This resulted in the aircraft entering the airspace completely Nordo; with my R-side unable to reach him even through Relaying through another Aircraft; and [ZZZ1 Center] not being able to reach him either. As he entered a 065 MIA area.Suggestion: Even though the aircraft was roughly 40min away from reaching terrain; for a non-radar handoff; in an area with radio issues; I should have climbed them upon taking the non-radar handoff immediately. I should have also omitted the lost comms entirely as it caused confusion with the pilot and resulted in them not monitoring the frequency; or I should have been much clearer with ZZZ1 Center; that the aircraft should still be attempting to contact us; as we can always relay through other aircraft; and most times they can hear us but we cannot hear them; or vice-versa. My poor communication with ZZZ1 Center resulted in a strange situation where the aircraft was Nordo and not attempting to reach out to us.