▁An amb as ▁and ▁many ▁smaller ▁islands . ▁There ▁were ▁also ▁several ▁territ ories ▁in ▁Ig al , ▁Ga ung , ▁R ete h ▁and ▁Mand ah ▁located ▁in ▁Ind rag iri ▁on ▁main land ▁Sum atra . ▁All ▁these ▁territ ories ▁were ▁head ed ▁by ▁a ▁Dat uk ▁K aya ▁( no blem an ), ▁known ▁as ▁an ▁Am ir ▁( equ ivalent ▁to ▁a ▁Vis count ) ▁who ▁had ▁been ▁chosen ▁by ▁the ▁s ultan ▁or ▁by ▁the ▁r uling ▁el ite ▁to ▁deal ▁with ▁the ▁local ▁administration . ▁ ▁Foreign ▁relations ▁and ▁trade ▁ ▁There ▁were ▁two ▁main ▁economic ▁and ▁commercial ▁sources ▁of ▁wealth ▁in ▁R ia u - L ing ga , ▁sp ices ▁( es pecially ▁pe ppers ) ▁and ▁tin . ▁The ▁Dutch ▁mon opol ised ▁the ▁trade ▁system ▁in ▁the ▁R ia u ▁arch ip el ago ▁even ▁before ▁the ▁partition ▁of ▁ 1 8 2 4 , ▁and ▁were ▁keen ▁to ▁control ▁the ▁region ▁after ▁gain ing ▁influence ▁following ▁the ▁Dutch - J oh or - R ia u ▁agreement . ▁ ▁Dutch ▁One ▁of ▁the ▁most ▁prominent ▁batt les ▁during ▁the ▁R ia u - D utch ▁wars ▁was ▁between ▁R aja ▁H aj i ▁and ▁the ▁Dutch ▁milit ia . ▁The ▁fight ▁against ▁the ▁Dutch , ▁led ▁by ▁R aja ▁H aj i ▁in ▁Tan j ung ▁Pin ang , ▁managed ▁to ▁prevent ▁the ▁Dutch ▁force ▁from ▁adv ancing ▁on ▁Mal ac ca . ▁In ▁June ▁ 1 7 8 4 , ▁R