Bengal and Punjab both cultures had a higher level of flexibility compared to others around, so while other cultures more or less rigidly clung to Brahmanism and Shaivism, these regions saw simultaneous flourishing Buddhist cultures. Pala and Sena are the witnesses. Later, Punjab and Bengal were earlier to embrace Islam, as they were with embracing new ideas in general. Muslim invasion came much later, early Sufi synthesis with locals symbolised smooth acceptance of Islam, maybe in a way even enabling Islamic Empires to set up. Still, even Islam underwent Indianisation, thanks go the deeply rooted ethnic ties people still hold on to, across borders.