Label it as a compound-complex sentence.
Pocahontas was only eleven years old when she met [John] Smith, and he left the New World two years later.
-- How They Croaked, page 52-53
Pocahontas was only eleven years old = independent clause (It could be a sentence by itself.)
when she met [John] Smith = dependent clause (If you took away the "when," the rest could be a sentence by itself.)
he left the New World two years later = independent clause (It could be a sentence by itself.)
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| Independent, Dependent, Independent |
