The Horde town of Tarren Mill offers many quests to players through their twenties. Later, Tarren Mill also serves as the Horde town for questing in Alterac Mountains, though there are considerably fewer quests to be done there.
Alliance quests in Hillsbrad Foothills are slightly higher level then their Horde couterparts, due to the long distance away from the rest of Alliance civilization. All quests come from the town of Southshore.
In this quest chain, players help the lazy Lieutenant Farren Orinelle with his assigned duty of clearing the coasts of southern Hillsbrad of the menace of the murlocs and naga that have taken up residence.
The troublesome ogre warlord Mug'thol (who you may remember from the Frozen Throne) has put on the Crown of Will, freeing he and his ogres from the mind control of Sylvanas. Of course, such rebellion merits swift retribution, and you play the part of the instrument of the Dark Lady's wrath.
Technically, all the quests in this chain take place in Alterac Mountains, however, it is still categorized under Hillsbrad Foothills in game because the quest giver is in Tarren Mill.