Who are "the shepherds and their flocks"?
Rashi, Targum Yonasan: This is a metaphor for kings and their soldiers [Radak - who come to destroy it. This is common in Tanach, e.g. "Klei Ro'eh Eveli" (Zecharyah 11:15), "v'Nasati Lahem Ro'im k'Libi" (above, 3:15).]
What is "Yado"?
Rashi: It is his place around [Tziyon]. Radak - this is like "Ro'os Al Yedeihem" (Iyov 1:14). I.e. one king or officer besieges one city or cities, and son another, until they finish conquering the land.
Malbim: It is what is near him. First they grazed and destroyed around Yerushalayim, then they wanted to come to Yerushalayim itself. The Navi compares the residents to a pampered who hides in her house in the afternoon due to the sun - "Eichah Tarbitz ba'Tzaharayim" (Shir ha'Shirim 1:7), and sleeps in the afternoon. At night she sleeps on her bed. The enemy thought to conquer her then.
