I would make an argument against putting Arabia and Persia as tier 1.
If we consider a tier 1 civ as something that is almost like playing on a lower difficulty level, I don't think these 2 civs have enough of a bonus.
Arabia: the bazaar is good to allow for lux trades with the AI and getting a bit more happiness, but I don't think its gamebreaking. the camel archer is indeed one of the best UUs in the game, but it requires you to build that unit and go to war with it. I admit that going through a bit of war is quite common, but you're forced to play with that plan in mind which some players don't like to do. their UA is not exceedingly impressive either.
Persia: 50% longer golden ages is equivalent to 1 wonder/social policy. the +1 movement is great but only for war as well. immortals are good but I don't think even with +1 move and 10% combat bonus it's that great as a unit because so many battles are won with ranged units. satrap's court is about the same level as the bazaar, more happiness and more gold is always nice, but it's not as blatant as the other bonuses we see tier 1 civs have.
Those 2 civs are very good, but they don't offer strong bonuses that you would benefit from regardless of your game plan and style. the 50% longer golden age is great, I admit, but the other benefits from these civs are not on the same level as poland babylon etc. for tier 1 civs I think the benefits should be strong, and accessible every single game regardless of your start or how you choose to play.
If we consider a tier 1 civ as something that is almost like playing on a lower difficulty level, I don't think these 2 civs have enough of a bonus.
Arabia: the bazaar is good to allow for lux trades with the AI and getting a bit more happiness, but I don't think its gamebreaking. the camel archer is indeed one of the best UUs in the game, but it requires you to build that unit and go to war with it. I admit that going through a bit of war is quite common, but you're forced to play with that plan in mind which some players don't like to do. their UA is not exceedingly impressive either.
Persia: 50% longer golden ages is equivalent to 1 wonder/social policy. the +1 movement is great but only for war as well. immortals are good but I don't think even with +1 move and 10% combat bonus it's that great as a unit because so many battles are won with ranged units. satrap's court is about the same level as the bazaar, more happiness and more gold is always nice, but it's not as blatant as the other bonuses we see tier 1 civs have.
Those 2 civs are very good, but they don't offer strong bonuses that you would benefit from regardless of your game plan and style. the 50% longer golden age is great, I admit, but the other benefits from these civs are not on the same level as poland babylon etc. for tier 1 civs I think the benefits should be strong, and accessible every single game regardless of your start or how you choose to play.

Or move, fire, move back. Sick. It also makes workers work much faster, since they can move 2 squares and begin improvement 

on a building you want in all cities is great, immortals are good for early defense and some offense (but upgrade into a not so useful line) and the UA is good (but not easy to control until you have GAs). I think this would make them Tier2.
bonus require that you send your TRs to city states, something you don't always want to do. Barb camps capture is highly unreliable (esp on Deity where you might end up with no camp to capture at all) and i tend to rank unreliable abilities lower.
