A team of small engineers inside AMD created Mantle, and AMD management did fuck-all with it; they donated it to Khronos for Vulkan, but some lawyers got involv

A team of small engineers inside AMD created Mantle, and AMD management did fuck-all with it; they donated it to Khronos for Vulkan, but some lawyers got involved and patent claims held up the release for a few years (Vulkan being late? That's AMD's fault!) So the team that mostly created Mantle left AMD, got hired by Apple, where they built Mantle 2.0, aka Metal.