▁society ▁was ▁on ▁the ▁ver ge ▁of ▁another ▁transition ▁phase ▁by ▁ 1 5 2 1 , ▁as ▁lat te ▁stones ▁became ▁bigger . ▁ ▁Assuming ▁the ▁stones ▁were ▁used ▁for ▁chief ly ▁houses , ▁it ▁can ▁be ▁argued ▁that ▁Cham or ro ▁society ▁was ▁becoming ▁more ▁strat ified , ▁either ▁from ▁population ▁growth ▁or ▁the ▁arrival ▁of ▁new ▁people . ▁The ▁theory ▁remains ▁ten uous , ▁however , ▁due ▁to ▁lack ▁of ▁evidence , ▁but ▁if ▁proven ▁correct , ▁will ▁further ▁support ▁the ▁idea ▁that ▁Pre - Contact ▁Cham or ros ▁lived ▁in ▁a ▁v ibr ant ▁and ▁dynamic ▁environment . ▁ ▁Spanish ▁era ▁ ▁Mag ellan ' s ▁first ▁encounter ▁with ▁Gu am ▁▁ ▁The ▁first ▁known ▁contact ▁between ▁Gu am ▁and ▁Western ▁Europe ▁occurred ▁when ▁a ▁Spanish ▁expedition ▁led ▁by ▁Ferdinand ▁Mag ellan , ▁a ▁Portuguese ▁expl orer ▁sail ing ▁for ▁the ▁Holy ▁Roman ▁Emperor ▁King ▁Charles ▁I ▁of ▁Spain , ▁arrived ▁with ▁his ▁ 3 - ship ▁fleet ▁in ▁Gu am ▁on ▁March ▁ 6 , ▁ 1 5 2 1 ▁after ▁a ▁long ▁voyage ▁across ▁the ▁Atlantic ▁and ▁Pacific ▁O ce ans , ▁from ▁Spain . ▁History ▁cred its ▁the ▁village ▁of ▁Um ata c ▁as ▁his ▁landing ▁place , ▁but ▁draw ings ▁from ▁the ▁navig ator ' s ▁di ary ▁suggest ▁that ▁Mag ellan ▁may ▁have ▁land ed ▁in ▁T um on ▁in ▁northern ▁Gu am . ▁The ▁expedition ▁had ▁started ▁out ▁in ▁Spain ▁with ▁five ▁ships . ▁By ▁the ▁time ▁they ▁reached ▁the ▁Marian as ▁they