Metsubushi
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Metsubushi (目潰し?) - "eye closers", the name for variety of techniques used to temporarily or permanently blind or disorient the opponent. Ninjas would use these for self defence or to facilitate their escape.
One kind is a powder made up of ashes, ground up pepper, mud, flour, dirt, for severe damage fine glass or salt, and other small powders. It was kept in a hollowed out eggs, bamboo tubes or other small container and when confronted by an attacker, a person would throw metsubushi in the attacker's eyes, blinding him, while the victim ran off or hid himself.
Other techniques would be blinding the opponent with light reflected of a mirror, or throwing any item at opponents head, making them instinctively close their eyes.
Flash and smoke bombs would also count as metsubushi, but since they're more complicated it's not likely they were used in ancient Japan.