▁East ▁and ▁the ▁F ert ile ▁C res cent , ▁and ▁the ▁agricult ural ▁techniques ▁of ▁that ▁region ▁were ▁adopted ▁wh oles ale . ▁This ▁included ▁a ▁different ▁set ▁of ▁cro ps , ▁such ▁as ▁whe at , ▁bar ley , ▁and ▁g rap es . ▁North ▁Africa ▁was ▁also ▁bl essed ▁by ▁one ▁of ▁the ▁rich est ▁agricult ural ▁regions ▁in ▁the ▁world ▁in ▁the ▁N ile ▁River ▁valley . ▁With ▁the ▁arrival ▁of ▁agricult ure , ▁the ▁N ile ▁region ▁became ▁one ▁of ▁the ▁most ▁dens ely ▁populated ▁areas ▁in ▁the ▁world , ▁and ▁Egypt ▁home ▁to ▁one ▁of ▁the ▁first ▁civil izations . ▁ ▁The ▁dry ing ▁of ▁the ▁Sah ara ▁created ▁a ▁form id able ▁bar rier ▁between ▁the ▁northern ▁and ▁southern ▁port ions ▁of ▁the ▁continent . ▁Two ▁important ▁exceptions ▁were ▁N ub ian ▁Sud an , ▁which ▁was ▁linked ▁to ▁Egypt ▁by ▁the ▁N ile ▁and ▁Eth iop ia , ▁which ▁could ▁trade ▁with ▁the ▁northern ▁regions ▁over ▁the ▁Red ▁Sea . ▁Power ful ▁states ▁grew ▁up ▁in ▁these ▁regions ▁such ▁as ▁K ush ▁in ▁N ub ia ▁( mod ern ▁day ▁Northern ▁Sud an ▁and ▁Southern ▁Egypt ) ▁and ▁A ks um ▁in ▁Eth iop ia . ▁Es pecially ▁from ▁N ub ia , ▁ideas ▁and ▁techn ologies ▁from ▁the ▁Middle ▁East ▁and ▁Europe ▁reached ▁the ▁rest ▁of ▁Africa . ▁ ▁Histor ians ▁believe ▁that ▁iron ▁working ▁ ▁developed ▁independently ▁in ▁Africa . ▁Un like ▁other ▁contin ents ▁Africa ▁did ▁not ▁have ▁a ▁period ▁of ▁co