'Nobori' (幟), literally meaning 'banner', had a more specific meaning on the battlefields of feudal Japan. It referred to a particular type of banner denoting units within an army; nobori became much more common in the Sengoku period, coming into use alongside the earlier hata-jirushi. They were long, narrow flags, attached to a pole with a cross-rod to hold the fabric straight out and prevent it from furling around the rod; this way, the flag would always remain visible and identifiable. The Sengoku Period (æ¦å½æä»£ Sengoku jidai) or warring-states period, is a period of long civil war in the history of Japan that spans from the middle 15th to the early 17th centuries. ... Hata-jirushi (æå°) were the most common of war banners used on the medieval Japanese battlefield. ...
Though usually used to represent different divisions within an army, nobori were sometimes made identical, so as to produce an impressive and intimidating display of warrior flags.