Albert Barnes Commentary Psalms 74:4

"Thine adversaries have roared in the midst of thine assembly; They have set up their ensigns for signs." — Psalms 74:4 (ASV)

Your enemies roar — This refers to the shout and tumult of war. They raised up the war-cry even in the very place where the congregations had been assembled, where God had been worshiped. The word translated “roar” properly refers to wild beasts, and the meaning is that their war-cry resembled the howling of beasts of prey.

In the midst of your congregations — literally, “in the midst of your assembly.” This is a different word from that which is translated “congregation” in (Psalms 74:2). This word — מועד (mô‛êd) — means a meeting together by mutual appointment and is often applied to the meeting of God with his people at the tabernacle, which was therefore called “the tent of the congregation,” or, more properly, “the tent of meeting,” as the place where God met with his people (Exodus 29:10, Exodus 29:44; Exodus 33:7; Leviticus 3:8, Leviticus 3:13; Leviticus 10:7, Leviticus 10:9; and often). The meaning here is that they roared like wild beasts in the very place which God had appointed as the place where he would meet with his people.

They set up their ensigns for signs — That is, they set up their banners or standards, as the standards of the place, as that which indicated sovereignty over the place. They proclaimed thus that it was a conquered place, and they set up their own standards as denoting their title to it, or as declaring that they ruled there. It was no longer a place sacred to God; it was publicly seen to belong to a foreign power.