The 'split reins' you are talking about are Western reins. 'Combined reins' are English. Both are good, just different riding styles.

No Reins was created in 1986.

you can buy reins at any normal tack shop, or you can order reins from a website

It depends on what kind (the correct spelling is rein instead of reign)

There are many types. There is a braided split reins, reins with rawhide braid, bitless bridle reins, a horse nylon headstall reins, rubber lined reins, camelot web reins, a barrel reins with rubber grip etc. etc.

In Western Riding are two styles of reins known:

- closed reins

-split reins or open reins

Split reins are used, if frequent dismounting is required. Their disadvantage is that they can accidently fall down. Usually they are longer than closed reins and kept crossed over the neck /wither area of the neck to prevent them from falling down.