To say they were ever "in contact" in the way that I think Temujin meant, is
pure unfounded speculation.
Aragorn's stint in the service of Ecthelion was incognito -- I doubt the rank
and file of Gondor's captains and lords ever knew who he was, no matter what
Denethor may have figured out.
Since the "Rangers" of Ithilien were probably an outgrowth of an established
irregular scouting force of Gondor's armies, and the "Rangers" of Eriador were
the tattered remnant of a once-great kingdom that had fallen out of contact
with Gondor, I don't see any basis for stating that they were ever "in contact"
in a meaningful sense, no matter what individuals of high rank like Aragorn, or
Denethor, may have known or suspected was going on in the opposite
kingdom.
