▁in ▁ 1 6 2 4 . ▁ ▁As ▁a ▁result ▁of ▁the ▁failure ▁of ▁negoti ations , ▁de ▁S ous a ▁under to ok ▁a ▁series ▁of ▁wars ▁against ▁N j ing a . ▁ ▁Two ▁major ▁wars ▁in ▁ 1 6 2 6 ▁and ▁ 1 6 2 8 ▁drove ▁N j ing a ▁from ▁the ▁King d ong a ▁Island ▁to ▁Mat amba ▁where ▁she ▁established ▁her ▁base ▁in ▁ 1 6 3 1 . ▁F it ful ▁negoti ations ▁followed , ▁and ▁in ▁ 1 6 3 9 ▁N j ing a ▁concluded ▁a ▁peace ▁with ▁Portugal . ▁ ▁At ▁the ▁same ▁time ▁Portugal ▁established ▁diplom atic ▁relations ▁with ▁Kas anje , ▁the ▁Im b ang ala ▁band ▁that ▁occupied ▁the ▁K w ango ▁River ▁valley ▁south ▁of ▁N j ing a ' s ▁domains ▁in ▁Mat amba . ▁ ▁Salvador ▁de ▁S á ▁sought ▁to ▁restore ▁Portuguese ▁authority ▁as ▁much ▁as ▁possible ▁during ▁his ▁rule ▁from ▁ 1 6 4 8 ▁to ▁ 1 6 5 2 . ▁ ▁However , ▁he ▁made ▁little ▁progress , ▁aside ▁from ▁forcing ▁N j ing a ▁to ▁retre at ▁from ▁her ▁position ▁in ▁Cav anga ▁to ▁Mat amba . ▁ ▁His ▁success ors ▁in ▁the ▁sevent e enth ▁century ▁sought ▁to ▁renew ▁the ▁war fare ▁that ▁had ▁expanded ▁Portuguese ▁authority ▁and ▁filled ▁slaves ▁ships ▁before ▁the ▁Dutch ▁inter l ude . ▁ ▁However ▁ag gress ive ▁foreign ▁policies ▁were ▁less ▁successful . ▁ ▁Following ▁a ▁dis astr ous ▁campaign ▁in ▁K