▁in ▁the ▁early ▁e ighth ▁century . ▁ ▁Al - W al id ▁was ▁succeeded ▁by ▁his ▁brother , ▁Sul ay man ▁( 7 1 5 – 7 1 7 ), ▁whose ▁reign ▁was ▁domin ated ▁by ▁a ▁prot ract ed ▁sie ge ▁of ▁Constantin ople . ▁The ▁failure ▁of ▁the ▁sie ge ▁marked ▁the ▁end ▁of ▁serious ▁Arab ▁amb itions ▁against ▁the ▁By z antine ▁capital . ▁However , ▁the ▁first ▁two ▁dec ades ▁of ▁the ▁e ighth ▁century ▁witness ed ▁the ▁continu ing ▁expansion ▁of ▁the ▁C ali ph ate , ▁which ▁pushed ▁into ▁the ▁I ber ian ▁Pen ins ula ▁in ▁the ▁west , ▁and ▁into ▁Trans ox iana ▁in ▁the ▁Muslim ▁con quest ▁of ▁Trans ox iana ▁( under ▁Q ut ay ba ▁ibn ▁Muslim ) ▁and ▁northern ▁India ▁in ▁the ▁east . ▁Arab ▁sources ▁claim ▁Q ut ay ba ▁ibn ▁Muslim ▁briefly ▁took ▁K ash gar ▁from ▁China ▁and ▁with d rew ▁after ▁an ▁agreement ▁but ▁modern ▁histor ians ▁entirely ▁dismiss ▁this ▁claim . ▁ ▁In ▁AD ▁ 7 1 5 , ▁the ▁Um ay y ad ▁C ali ph ate ▁de posed ▁the ▁ik h sh id ▁of ▁the ▁Princi p ality ▁of ▁F arg h ana , ▁and ▁installed ▁a ▁new ▁king ▁Al ut ar ▁on ▁the ▁throne . ▁The ▁de posed ▁king ▁fled ▁to ▁K ucha ▁( se at ▁of ▁An xi ▁Prote ctor ate ), ▁and ▁sought ▁Chinese ▁inter vention . ▁The ▁Tang ▁dynast y ▁sent ▁ 1 0 , 0 0 0 ▁troops