Barlok the Wise the chief of the tribe of martians Croach the Tracker was born into, and also the tribe who raised The Red Plains Rider. He has been the chief of Croach's tribe for an unknown amount of time, but since before Sparks Nevada came to Mars.
In Christmas on Mars, Barlok was leading his people to another location on Mars after their defeat in the second War of Two Worlds. The tribe's space oil had been stolen after bandits knocked out Sparks Nevada, who had been in charge of guarding the oil. Sheb the Comptroller told Barlok they only had 1/8th of the space oil they needed, but Sheb instead turned out to be Chulp the Imposter. Also, Sparks Nevada was able to track down the outlaws who stole the oil and return it to the tribe.
Later, when Sparks Nevada saved the entire tribe from death by lassoing up a flood with a wormhole generator, Barlok assigned Croach the Tracker to help track Sparks' "metal enemies" (robot outlaws) to fulfill the onus the tribe incurred upon being saved.
After Sparks refused Croach's continued help between Flood at First Sight and The Sad, Sad Song of Widow Johnson, Part One, Barlok found Sparks and implored him to allow Croach to fulfill the tribe's onus to Sparks, then quickly left, with only Croach remaining behind.