<p>"From about AD. 700 to 1600, sculptors [created/have created] nearly 1,000 colossal rock statues on the remote and tiny Easter Island."</p>
<p>I was wondering what this rule is called, and how do you know which one is correct? Can someone please explain when you use the past tense and when you use have/had + past tense? Thanks!</p>
<p>(The correct answer is created)</p>
<p>“Have created” indicates something that is still going on in the present.</p>
<p>here is an easy shortcut ,
if any dates or mentioned historical period just use simple past
however if ( since / for ) were in the sent. directlyuse present perfect
if there are 2 verbs in the sentence , always the verb that happened first is used in past perfect
finally last note about verbs , make sure that the form ( have/has/had + past participle) is used correctly
I hope I have helped 
good luck tomorrow</p>