Biological warfare was effective against the Inca because there immune system's were not used to that type of diseases that Europeans brought over. There are very susceptible to disease and were wiped out quickly
The Emperors needed the church to maintain power
Because once an indentured servants time is up, you have to let them live their own life, but if you have a slave, you literally own them and keep them until they die if you choose to do so.
Indian civilizations from earliest to latest.
1. Gupta Empire (320 -335 AD) Chandragupta (founder)
2. 4. Ghaznavid Empire (977-1186) Sabuktigin (founder)
3. Ghurid Dynasty (1011–1035) Abu Ali ibn Muhammad (first Muslim king
4. Delhi Sultanate (1206–1526) Qutab-ud-din Aibak (founder of the Mameluk of Slave Dynasty)