Return to the light sand spit and head West, and you’ll spot a backpacker wandering around on top of a dune, apparently trying to gather sand?

Battle: Backpacker Clara (528 Poke)
Opponent: Sandshrew Lv 22

Her Sandshrew is strangely fond of Swift, which is not even slightly an optimal attack for it.

Moving on to the West, you can pull a Blue Shard from the bottom of a sandpit.  Keep going and you’ll find a Red Shard to go with it in a wall-nook, with another backpacker out front.

Battle: Backpacker Sam (528 Poke)
Opponent: Dwebble Lv 22

Sam’s Dwebble has Sand Attack, which can make it a defensive terror, so make sure you pack something that can take it out quickly, or can endure the sandstorm for a long time. 

Once you’re done with Sam, step North and move around the rock to the West.  Head South behind it to find another backpacker looking for a battle.

Battle: Backpacker Tami (528 Poke)
Opponent: Drilbur Lv 22

Tami’s Drilbur is a Sand Force Drilbur, so just make sure you’ve got something quick to hit it hard, or it’ll put a nasty dent in your team.  Past Tami to the South, you can meander around a few rocks and plateaus.  A Max Ether waits on the West side of this odd path, but that’s really all that’s back here.