After spotting the red escape light of the Eastern Sect Master heading towards the Medicine God Valley, some of the Sect's Golden Core Real Persons followed from a distance, wanting to see what would occur. If the Medicine God Valley was wiped out, they'd be able to take advantage of the situation.
As for the Nascent Soul True Monarchs of the various sects, they hardly reacted. If the Golden Core Real Persons wanted to crowd around that was fine, but if they, the Nascent Soul cultivators, followed, they might anger the Eastern Sect Master.
The first sect to notice the red escape light was the Liu Yun Sect. A Golden Core Real Person who was patrolling the area immediately reported it to the Sect Master.
Later, upon consolidating various pieces of intelligence and learning that the Eastern Sect Master was going to the Medicine God Valley, Green Jade Zen Ren went to Gold Sword True Monarch's retreat in the Cave Mansion to report.