More things we were not taught in school

Texans profited by selling whiskey to Indians across  the river 

“In 1837-1838, the Acting Superintendent of the Western Territory, William Armstrong, reported that the south side of the Red River below Fort Towson was largely settled by white men who earned their livelihood by vending spirits to the Indians. Armstrong considered the situation so desperate that he requested two companies of dragoons to be ordered to the fort for the purpose of protecting the Chickasaw emigrants who were in the process of being removed from Mississippi. Besides whiskey-runners, many unscrupulous persons frequented the Indian country with games of chance, hoping to cheat the Indians out of their property.

“Although most Indian citizens obeyed their laws, a number yielded to temptation. The relative ease in crossing the Red River at certain points led to an increase in whiskey business in Texas. Whiskey shops and distilleries dotted the southern banks of the Red, and moved steadily westward as settlement itself moved to the west. Agent Upshaw estimated in 1843 that two-thirds of the whiskey brought into the Nation came in from Texas. The beverage was not always transported across the border by citizens of Texas; some Indians crossed the Red themselves, entered the taverns on the Texas side, gave their guns and horses for two or three gallons of whiskey and then carried it back into Indian Territory.

“By 1849, grocery stores on the Texas side openly sold liquor to the Indians and did a flourishing business. The volume of business grew to such an extent that they could even afford to reduce their prices. Agent Upshaw reported that two steamboats plied the Red River whenever the water level was high enough, and though they were trading boats with all manner of merchandize, they trafficked largely in the sale of liquors. The business had now approached a boldness almost unknown in past years. Indians could not (now?) obtain a quart of firewater for one bushel of corn. The steamboats were attempting to undersell the local establishments on shore.”

https://digital.library.unt.edu/ark:/67531/metadc663163/m2/1/high_res_d/1002774119-Graffham.pdf

That immediate problem was settled through movement of more law-abiding people into Texas, leading to political and moral pressure to do the right things. Southeast Oklahoma and Northeast still have illegal whiskey sales, but nowhere near the volume of the mid-1850s to 1950s.