silk. During the Qing dynasty (1644–1912) the strings transitioned to only wires such as brass. Modern strings are almost always steel coated in nylon. First introduced in the 1970s, these multi-material strings increased the instrument's volume while maintaining an acceptable timbre. The guzheng is often decorated. Artists create unique cultural and artistic content on the instrument. Decorations include carved art, carved lacquer, straw, mother-of-pearl inlays, painting, poetry, calligraphy, shell carving (jade), and cloisonné. Guzheng music has similarity with folk songs, it is developed on the basis of people's life. Through the performance of performers, it reflects the production and life of people at that time. Styles and techniques The guzheng is plucked by the fingers with or without plectra. Interestingly, among the 21 strings of Guzheng, although no strings are specifically assigned to play F or B, those pitches can be produced by pressing E and A instead, respectively. Most modern players use plectra that are attached to up to four fingers on each hand. Ancient picks were made of mundane materials such as bamboo, bone, and animal teeth or by finer materials such as ivory, tortoiseshell, and jade. Traditional playing styles use the right hand to pluck notes and the left hand to add ornamentation such as pitch slides and vibrato by pressing the strings to the left of the movable bridges. Modern styles use both hands to play on the right side of the strings. There are many techniques used to strike notes. One iconic sound is a tremolo produced by the right thumb rotating rapidly around the same note. Other guzheng techniques include harmonics (Fanyin) where one plucks a string while tapping it at the same time, producing a note in a higher octave. Many guzheng techniques have been borrowed from other instruments. For example, Lun is a borrowed technique. In Lun, all five fingers pluck on a string to produce a tremolo sound similar to the Pipa. Techniques can also vary in Northern and Southern China, producing different sounds and styles. Northern China Northern styles include songs from the Shandong and Henan regional schools. Songs from Shandong include "High Mountain and Flowing Water [Shandong Version]" (Gao Shan Liu Shui) and "Autumn Moon Over the Han Palace" (Han Gong Qiu Yue). Songs from Henan include "High Mountain and Flowing Water [Henan Version]" and "Going Upstairs" (Shang Lou). According to Samuel Wong, songs from Henan are fiery. Left