My Teacher teach me that in order to know that something that happen is come from bad or good karma, we need to see at the result.
For example a child who born in a rich family and grow up to be spoiled and end up enjoy in samsaric life, do nothing this is come from bad karma but for another child who born in a poor family and has difficulties in a childhood but when grow up this child turn to spiritual path this is come from good karma.
So many of high lamas left from tibet in crisis time, went to other countries especial in the west, it come from good karma also as now buddhist is spreadi to all over countries in the world especial in the west.