Check out example codes for "refusing to merge unrelated histories". It will help you in understanding the concepts better.
Code Example 1
git pull origin master --allow-unrelated-histories
Code Example 2
git pull --allow-unrelated-histories origin master
Code Example 3
git pull origin master --allow-unrelated-histories
#IF THAT DOESN'T WORK, REPLACE 'origin master' WITH THE REPO YOU WANT TO PULL FROM
Code Example 4
git pull origin branchname --allow-unrelated-histories
Code Example 5
git pull origin master --allow-unrelated-histories
Code Example 6
git pull origin master --allow-unrelated-histories
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