Guido of Arezzo
In the 12th century, a development in teaching and learning music in a more efficient manner had arisen. Guido of Arezzo's alleged development of the Guidonian hand, more than a hundred years after his death, allowed for musicians to label a specific joint or fingertip with the gamut (also referred to as the hexachord in the modern era). Using specific joints of the hand and fingertips transformed the way one would learn and memorize solmization syllables. Not only did the Guidonian hand become a standard use in preparing music in the 12th century, its popularity grew more widespread well into the 17th and 18th century. The knowledge and use of the Guidonian hand would allow a musician to simply transpose, identify intervals, and aid in use of notation and the creation of new music. Musicians were able to sing and memorize longer sections of music and counterpoint during performances and the amount of time spent diminished dramatically.
Hand cannon
Hand cannons first saw widespread usage in China sometime during the 13th century and spread from there to the rest of the world. In 1287 Yuan Jurchen troops deployed hand cannons in putting down a rebellion by the Mongol prince Nayan. The earliest artistic depiction of a hand cannon – a rock sculpture found among the Dazu Rock Carvings – is dated to 1128, earlier than any recorded or precisely dated archaeological samples, so it is possible that the concept of a cannon-like firearm has existed since the 12th century. The oldest extant hand cannon bearing a date of production is the Xanadu Gun, dated to 1298. The Heilongjiang hand cannon has been dated to no later than 1288, but this dating is based on contextual evidence; the gun bears no inscription or era date. Other specimens also likely predate the Xanadu and Heilongjiang guns and have been traced back to the Western Xia period, but these too lack inscriptions and era dates.