The world 's first urban centers rose centuries earlier in the lower valley of the Tigris and Euphrates Rivers , known as Mesopotamia in antiquity , now part of Iraq .
Iraq /location/location/contains Tigris
DT NN POS JJ JJ NNS VBD NNS RBR IN DT JJR NN IN DT NNP CC NNP NNP , VBN IN NNP IN NN , RB NN IN NNP .
Iraq
LOCATION
Tigris
LOCATION
/location/location/contains