What's the deal with high pass gnolls

[zillabunny]

I am a 16 druid and my buddy is a 16 necro

We were getting bored with beetles in unrest so we decided to go scalp hunting in high pass. We killed 1 or 2 gnolls and then all of a sudden ed like 6 gnolls steam rolled us we managed to zone out and med back up we fired someone trained us and said nothing even tho we saw no one....

Fast forward we kill 3 or 4 more gnolls and then boom same thing like 4 gnolls just roll into the zone line out of nowhere!

We are almost ready to head back to unrest (we didn't rebind) but like is it mandatory to have a full 6 group to hunt the gnolls here or is this something we are doing wrong?