The Sarmatians fielded large numbers of heavily armour lancers, but few were really cataphracts proper.

Baktria and the Seleucids fielded cataphracts to counter those of Armenia and Parthia.

Even the Parthians though seemed to have changed practices and moved to more lightly armored, more mobile, and cheaper to train and equip lancers that also had bows standard shortly after 300 AD.
The parthians were gone by then, replaced with the Sassanids. Also, note that most, if not all, cataphracts had bows anyways (take a look at the EB cataphract models...2 weapon system sucks ): ). Also, the top cataphracts armour only improved during Sassanid times - the ERE offered stiff competition.