About: http://webisa.webdatacommons.org/146820868

Property	Value
http://www.w3.org/1999/02/22-rdf-syntax-ns#type	http://www.w3.org/ns/prov#Entity
http://www.w3.org/ns/prov#value	Mounted units are a large part of a balanced army, and the UB lasts fairly long, even longer in BtS. If other civs could not build Stables this might be overpowering, which is likely why the Stable was added for all civs as well.
http://www.w3.org/ns/prov#wasQuotedFrom	civfanatics.com