What is the meaning of 'Sulh-i-Kul'?

NCERT (Pre-rationalised): “5.2 A unifying force … Mughal chronicles present the empire as comprising many different ethnic and religious communities – Hindus, Jainas, Zoroastrians and Muslims. As the source of all peace and stability the emperor stood above all religious and ethnic groups, mediated among them, and ensured that justice and peace prevailed. Abu’l Fazl describes the ideal of sulh-i kul (absolute peace) as the cornerstone of enlightened rule. In sulh-i kul all religions and schools of thought had freedom of expression but on condition that they did not undermine the authority of the state or fight among themselves.…”