thuggish

Their thuggish manner made continuing negotiations very difficult.

[…] beside the deceitfulness of the heart and the carnality common to all men, the deep ignorance of the heathen, the abjectness of their social condition, their vain but venerated traditions, their time-honored customs of profligacy, impelling to infanticide, parricide, Thuggish murders, and cannibalism—all conflict steadily with the holiest efforts to transform them into symmetrical Christians.