ixc came before sc. Here is the order as I remember btc nmc ixc ioc sc gg tbx fbx ltc sc2 ruc. nmc started it all. ixc was created with 500K premined casuing ioc to be created a couple days later. SC was created then gg was created to take shorter block times to an extreme. sc1 was also criticized. tbx was created to beat sc2 to cpu mining, fairbrix was created without the pre-mine and ltc was just done as a team to actually be a currency and compete with sc2. ruc was just a coin started in Russia.
Nice condensed historical account of the alt-chains.
