A big stack of leather bound folios can be found in the Great Library of Akkash (along the back wall of the first floor, local history section). They detail 400-500 years worth of human efforts to eradicate lizardmen from the wetlands near Akkash. These expeditions seem to fall into and out of fashion, which may account for the fact that, in 500 years, no ground has really been gained or lost. The wetlands of Akkash are still no more or less dangerous than they ever have been.
Some folios detail recovered objects (a mixture of crude weaponry, household objects, and totemic items) but the writers of these folios (who may or may not be the explorers themselves) have not made any effort to interpet which objects are most valuable to the lizardmen. (It all looks like rubbish, basically.)
No attempt to interpret lizardman culture or religion based on these expeditions has been made, despite the obvious strategic advantage this would provide. The main Akkashi sources for language and lore are actually much older. Many Akkashi citizens have knowledge of the lizardman language, but this actually predates even the folios. At some point centuries ago, research into lizardmen was a greater concern. This has essentially stagnated.
It seems these expeditions merely calm the populace, even if no decisive victory can ever be won.