All Caste are an ancient group of monks who've been in existence for millennia, and trained Jason Todd after his resurrection. They first appeared in Red Hood and The Outlaws #1 (September, 2011) and were created by Scott Lobdell.
The All Caste is an ancient group of warrior monks hidden in the Himalayan mountains that have been around for thousands of years. Ducra, their leader, claims to have lived for over three thousand years.
The All Caste had operated for millennia lead by the ancient Ducra. Talia al Ghul would find a young, recently resurrected, brain dead Jason Todd, heal him with the use of the Lazarus Pit, and bring him to the caste in secret, with the intent of having Ducra continue the former Boy Wonder's training. After Jason's training, he would eventually adopt the identity of the Red Hood in his return to Gotham.
Shortly after both Jason Todd and Starfire free an imprisoned Roy Harper from a Qurac prison, Jason is contacted by an old acquaintance, Essence, from the caste. She informs Jason that the caste had been attacked by an entity known as The Untitled. Jason travels to the caste's base where he finds the dead body of Ducra, whose spirit informs him of the attack. The team is attacked by the reanimated corpses of the caste members, and once they defeated Jason's former mentors, they go after The Untitled.