Self-Help Groups (SHGs) are indeed supported by Regional Rural Banks and Scheduled Commercial Banks, which often act as facilitators and provide credit linkages. The principle of group guarantee is fundamental to SHGs, where all members collectively vouch for any loan taken by an individual member. While early initiatives by banks like SBI contributed to microcredit, the broader SHG movement's origin is often attributed to a more diverse range of actors and methodologies, including NGO involvement.