I see what Joe was saying since they nearly wiped out Native Americans and the history of Christianity has allot of blood on it though it's been accumulated over a couple centuries rather than within a decade.
Either way you can't say "worse" as any mass loss of life is equally bad. Even if we had an actual count of the lives taken in the name of Christianity, what decides that these 2,000 here or 500 there are any more or less of a detriment to mankind and the evolution of society?
You also must take into account that you cannot truly judge such heinous crimes by the value of numbers as every life can have a purpose however grand or small!
Also consider that there may have been people whom, in a seat of power, would have spilled more blood than both combined however they were perhaps killed amidst the various slaughters we speak of. With the realization that at such a high death count there's no way to know who, if left alive, would have done what but it is very likely someone may have done worse, the question then would become; was it a good thing? See this train of judgement and logic can go on endlessly.
What must ultimately be realized with such death tolls is that it is neither good or bad it simply is and that must be accepted.
However this does not apply in the case of the shamans as they had good intentions, this anyone who is enlightened can be sure of. It was a small group that wished to share the sacred knowledge of truth and light gathered and passed down their lineage since it began, which may very well have been the dawn of modern man, with the world to help better all of humanity. The value of that is above any human life which could not offer the same I.M.O. and I even would trade my own for there's were it possible. However it is not and still while truly a sad loss it must be accepted.
I can only hope those that remain can be protected from such atrocities. In fact I would ask that all who read this meditate and put your energies towards that protection and ask those you know who would understand to do the same. I would also ask that you seek the protection of the light beings you meet on your journeys for them.
Otherwise lets find the joy and hope found in the future of those that remain and have the same intentions to better the world. The past cannot be changed and we must look to the future!
Namaste