Arizona is one of the places that a lot of aluminum got used and abused as house wiring.
Really old buildings and homes will most likely have copper wire in them, not aluminum.
Aluminum is an artifact of high copper prices of the mid 1960s. It conducts and it can be substituted for copper.
Aluminum house wiring is not dangerous per se. Its a good conductor and it behaves.
But, depending on how it was installed, it has some nasty side effects which are dangerous. First off, for a given leg of wiring, what could be done with 14 gauge copper should perhaps be 12 gauge aluminum. Many contractors did not do that. They just stuck with 14 gauge aluminum. It saved a few bucks.
Another side effect is that aluminum needs to be pigtailed or connected to copper end points. Those connections can come loose and can cause fires. Aluminum heats up and therefore expands more than copper so it will creep back n forth (potentially) in size. Connections get loose. Bad things can happen.
Properly installed, meaning the proper gauge for the run and proper connections, aluminum is just another choice for wiring. The real evil was contractors who substituted it for copper without upping the gauge required or using cheap connection points bound to loosen up.
Knowing all that is nice. If I ever found a property to buy and it had aluminum wiring in it, I'd still have it replaced.