I am not necessarily a fan of lengthy sentences, or of simply caging somebody, unless that person has demonstrated and continues to display uncontrollable violent tendencies from which the public deserves, and must have, protection. Public protection absolutely must be paramount. Rehabilitation, if and where possible, is the next priority, which includes meaningful support in the host community to the maximum extent possible.
New York reduced crime drastically, many years ago, by treating even minor crimes seriously. That discouraged many minor offenders from escalating to bigger crimes. They quickly understood that throwing a stone through a window would result in arrest, a cell overnight, a trial, and an appropriate sentence rather than just a stern talking-to and immediate release following a promise to behave.
Failure to effectively discourage/deter is unacceptable - it helps nobody, especially the offenders, who merely, correctly, and rapidly learn that they can get away with almost anything, often until somebody is seriously hurt or killed.
The carrot (and carrots are infinitely preferable if and when they work) to that stick is meaningful provision of work-related training and job-finding assistance.
Band leaders - too-often corrupt and abusive towards their own people - need to be exposed and held to account as part of that process. I would, if able, eliminate payments to bands and, instead, provide payments to individual adults. Band leaders could then apply taxes to their members to support necessary programmes. Ordinary members would then see how much is being taken from them, and would have more interest in controlling excesses (such as the legendary multi-million-dollar off-reserve Chief's house, if such actually exist).
Kind of like democracy.
I have a long-time indigenous friend who lives off of, but works on, a small reserve, and hear regular tales of the favouritism and outright nepotism and other abuses and problems that abound. There are no apparent off-reserve problems as far as I know, like the reserve at the centre of this conflict.
This is not an indigenous problem. many people of any race or ethnicity, when provided with the bare necessities of life and no incentive to do better, such as many welfare recipients. Payments should not be clawed back dollar-for-dollar for money earned from employment, either, as there is no incentive to work if one ends up with the same amount of money.
People who work have much more self-esteem than those who do not, have more regard for the things that they can buy with earned income, more respect for the rights and property of others, and much less need to relieve their boredom by drinking heavily and harassing farmers or other productive people.
People need hope for better futures, preferably via their own efforts but with assistance when needed. The opposite is despair.