The "Church History" Primary Manual lies about the "Mission to the Lamanites".
The difference can be seen by comparing these two sources
From the Primary Manual:
But missionaries of other churches were jealous and asked the United States
government to keep the Latter-day Saint missionaries out of the Indian territory.
The elders were soon forced to leave Chief Anderson’s people. They returned
to Independence and taught white settlers in that area. Source
From a BYU Studies Journal:
"Richard W. Cummins, the Indian agent learned about the elder's activities and ordered them to desist and leave at once. Government regulations forbade work among the Indians without a special permit issued by the Superintendent of Indian affairs, a regulation with
which the elders had failed to comply." Source
Differences
The Primary Manual does not say that the Mormon Missionaries were breaking the law by preaching to the Indians. The

Source: BYU - Studies - Mission to the Lamanites
Map of the Border Area between Kansas and Missouri.

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