How many centuries after the Sarmatians started their westward migration did they come to dominate the closely related Scythians?
return the  Sarmatians started their westward migration ;return they come to dominate the  closely related Scythians ;return when  was  #1 ;return when  was  #2 ;return difference of #4 and  #3 in  centuries
['select', 'select', 'project', 'project', 'arithmetic']