What is needed for long term rental

Yes you can rent a place in Bahrain just by showing your passport. Some places migh be iffy about it but mostly it should be ok. I live in Seef in Bahrain and I know my bedroom which has 2 bedroom fully furnished flats is quite relaxed when it comes to rentals.

You can rent easily here in Bahrain just using your passport. They do usually ask for your contract of employment though so you might have some questions to answer.

In Bahrain if you don't pay your rent or don't comply with the contract they can throw a travel ban on you so you are forced to pay up. Pretty hard to do if you don't live here. SO you may not get somewhere nice.

Best bet is to come here and use hotel serviced apartments or advertise looking for a room in a shared house. Not very nice but practical.

From what I have heard in UAE you need a full residency permit before you can rent there.