Judea has always been a key part of the "land bridge" that connects what we now know as the Arab world, specifically north Africa and the Middle East.
In biblical times, Judea was the gateway by which Egypt attacked Middle Eastern countries, and vice-versa. In 146 BC For instance, Ptolemy VI, aided by Jonathan Macabee, had invaded Syria and captured Selucia. That's why Antiochius VII Sidetes found it necessary to bring Macabee's nephew, John Hyrcanis to heel.
Earlier on, Nebuchadnezzar of Assyria had dissolved the Judea of its last king, Zedekiah, when the latter had allied with Egypt in order to start a rebellion.
Your earlier recollection about mountain fortresses is correct. Judea is located on a plateau, through which north-south trade routes pass through (and can therefore be blocked by) strongly fortified cities. Perhaps the strongest, and certainly the most famous of these cities is Jerusalem. According to Wikipedia:
During its long history, Jerusalem has been destroyed at least twice, besieged 23 times, attacked 52 times, and captured and recaptured 44 times.
This gives one an idea of the strategic importance of this city, and others around it.