ite ▁Sen oi ▁Pra a q ▁unit ; ▁a ▁special ▁unit ▁consists ▁of ▁Or ang ▁As li ▁( ind igen ous ▁tribe ) ▁expert ▁in ▁tracking . ▁The ▁last ▁' black ▁area ' ▁in ▁B idor , ▁the ▁G ep ai ▁F alls ▁was ▁finally ▁opened ▁to ▁public ▁in ▁ 1 9 8 9 ▁after ▁a ▁treat y ▁was ▁signed ▁between ▁Malays ian ▁government ▁and ▁the ▁Mal ay an ▁Commun ist ▁Party . ▁ ▁Econom y ▁ ▁B idor ▁is ▁a ▁mainly ▁industrial ▁area . ▁When ▁one ▁travel s ▁north ▁of ▁B idor , ▁one ▁will ▁see ▁miles ▁and ▁miles ▁of ▁plant ation ▁on ▁both ▁side ▁of ▁the ▁tr unk ▁road ▁covered ▁with ▁l ush ▁green ery , ▁gu ava , ▁oil ▁pal m ▁and ▁rub ber ▁plant ations . ▁ ▁An ▁important ▁source ▁of ▁income ▁for ▁the ▁town , ▁though , ▁is ▁( or ▁used ▁to ▁be ) ▁from ▁trav ellers ▁who ▁stop ▁by ▁the ▁town ▁for ▁its ▁well - known ▁local ▁del ica cies ▁and ▁agricult ural ▁products . ▁ ▁Before ▁the ▁advent ▁of ▁North – S outh ▁Express way , ▁trav ellers ▁had ▁no ▁choice ▁but ▁to ▁pass ▁through ▁this ▁town ▁through ▁the ▁federal ▁tr unk ▁road . ▁As ▁this ▁town ▁is ▁( st ill ▁is ) ▁rather ▁famous ▁for ▁its ▁variety ▁of ▁food , ▁trav ellers ▁frequently ▁choose ▁to ▁stop - by ▁at ▁one ▁of ▁the ▁e ater ies ▁before ▁continu ing ▁their ▁journey . ▁ ▁Ka olin ite ▁( ka olin ), ▁a ▁type ▁of ▁cl ay ▁was