Before going into hiding, He Song had already chosen his place of refuge.
The place of refuge was in the Golden Snake Sect, which was far away from Hu Prefecture, where He Song had previously purchased his needed items.
The main reason He Song purchased these items in Purple Cloud Sect's Hu Prefecture was because of its closeness to the Purple River Bank where he now resides.
The Purple River Bank is located within the Purple River State of the Golden Snake Sect.
Hu Prefecture is within the boundary of the Purple Cloud Sect.
Although it would not be entirely inaccurate to say that these two places have nothing to do with each other, being within the influence of different Nascent Soul Sects, no one would naturally associate them together.
After purchasing all the items he needed in Hu Prefecture, He Song quickly left and arrived in Purple River State.
Even if someone was trying to trace him, it would be impossible for them to use the information available to locate He Song.