did the AS use HA?

[Vasiliyi]

I was wondering if it would be historically accurate for me to include ha's in my army as arche selukia. they would be an amazing help for killing off other horse archers. Thanks for the help.

[AntiochosMegas]

Seleucids followed a lot the Alexander heritage and Alexander used HA in his campaign in Indus valley. Also is mentioned in battle of Magnesia the use of a unit of Dahae HA. Probably more HA units used by the Seleucids in their endless wars.

[ThePianist]

1000 out of 3000 (Seleucid) cavalry mentioned in 147 BC were horse archers. Previously such types had been recruited from Scythians or Parthians, by this stage Arabo-Arameans are likely to have been an important source. As the only cavalry type specifically mentioned by the sources, they are compulsory.
source (http://www.ne.jp/asahi/luke/ueda-sarson/LateSeleucidDBM.html)