The Knights Templar and La Familia Michoacana are one and the same. Technically, La Familia became the Knights after La Familia was decimated by convictions and by external and internal conflicts. They have thrown an extra religious angle into their name to help to gain the support of local people in Mexico who are mostly Catholic and very devout. They claim to defend Mexico as the Knights Templar defended the Holy Grail (except the whole selling drugs thing lol).

Basically, all of the modern cartels (Sinaloa, Tijuana, Juarez, the Gulf) are all descended from Miguel Ángel Félix Gallardo's Guadalajara Cartel. He split up his cartel to make it able to withstand indictments. Eventually, the newly formed cartels became rivals and the rest is history.