Https://www.pbs.org/wgbh/pages/frontline/shows/religion/why/appeal.html
the first website is why christianity was appealing back then,
the second website is why islam religion was succesful
https://askanislamicist.wordpress.com/2014/07/14/why-was-the-islamic-expansion-successful/
Answer:
The basic doctrines of early Buddhism, which remain common to all Buddhism, include the four noble truths: existence is suffering (dukhka); suffering has a cause, namely craving and attachment (trishna); there is a cessation of suffering, which is nirvana; and there is a path to the cessation of suffering, the eightfold path of right views, right resolve, right speech, right action, right livelihood, right effort, right mindfulness, and right concentration. Buddhism characteristically describes reality in terms of process and relation rather than entity or substance.
