If the Hausa are as you describe the, then indeed it is sad.
But I am not surprised. Violence is endemic among many people. The causes are many, but you should note that the very learned and civilized nations of the world, Christian included, have also engaged in large-scale violence, to the present day.
This does not excuse the Hausa, or other Muslims. Perhaps some of them have lost real understanding of Islam.
This loss of understanding and practice occurs among all people, unless a continuous effort is made.
It is also possible that the Christians are not entirely blameless.
The way to correct this is through Dawah and prayer. It is not in any one's hands to change the hearts (and practices) of individuals or nations. Only Allah (swt) can do that, but we are enjoined to take the Dawah to others.
However, we should examine
○ if we are ourselves abiding by the principles of Islam,
○ if we are aware that Islam brings ease, not hardship,
○ that while we have to give Dawah through our actions and words, we cannot change anything.
Live an exemplary life. See the Seerah of the Prophet (saw) and his companions (raa). Then tell others how they lived, how careful they were lest an injustice is done by them, and how they well treated the non-Muslims.
And pray. Get up in the last third of the night, pray Tahajjud, and ask Allah to bring the ummah of His last Prophet back to His deen.