How Bach contributed to the rise of Baroque period.

Bach was fluent in contrapuntal inventions and motivic control. With his ability to improvise keyboard music, his exposure to German, Italian and French music, and his devotion his religion, he had refined repeatedly his personal music style. His was able to gain access to musicians, scores and instruments when he was young, and this gave him a foundation to develop his own style.
He was able to inject foreign influences to intensify the pre-existing German music. Throughout the earlier stages of his life, he became more skillful in organizing large-scale musical ideas and enhancing the limited complexity of counterpoint. When a large repertoire of Italian music became available to him during his stay at Weimar, he absorbed the dramatic openings, clear melodic lines, the sharp outlines of their bass lines, rhythmic conciseness, and more clearly articulated schemes for modulation. This soon became a signature of Baroque music, and although composers like Shostakovich uses the Baroque forms and genres to write pieces, they are not completely Baroque.
There are several more specific features of Bach's influence on Baroque style. Composers were assumed to write out only the basic framework of the melodic lines, and the performer or player would insert a variety of ornaments, embellishing and elaborating on the basic notation. Bach, in his pieces, particularly the fast movements, notated most of the details of his melodic lines, giving the performer no freedom to interpolate. He was regarded as the extreme end of the spectrum as this practice of notation varied between different music schools. This may have helped him control the dense contrapuntal textures which did not allow performers to spontaneously vary the musical lines.
Bach’s devotion to his tradition and the high demand for religious music placed sacred music at the centre of his repertory; masses, chorale hymn tunes, were the basis of much of his output. He gave the chorale prelude a tightly integrated architecture, in which the interval patterns and melody of the tune was a dense, contrapuntal lattice against relatively slow-moving, overarching statements of the tune. Bach's deep knowledge of liturgy gave him an intricate relationship between music and linguistic text. Beyond these specific musical features arising from Bach’s religious affiliation is the fact that he was able to produce music for an audience that was committed to serious, regular worship, for which a concentrated density and complexity was accepted.
He preferred not to pursue more dramatic musical innovations, but was inclined to reinvigorate existing forms. Thus, Bach’s genius was almost entirely directed towards working within the structures he inherited. Keyboard music occupied a central position in his output throughout his life, and he made the keyboard a solo instrument in his numerous harpsichord concertos and chamber music with keyboard obbligato. Many of his keyboard preludes can be freely improvised to display virtuosity, although they get more and more cogent as he aged. He was driven to encompass whole genres by producing collections of movements that thoroughly explore the possibilities inherent in those genres. The most famous examples are the two books of the Well Tempered Clavier, each of which presents a prelude and fugue in every major and minor key, in which a variety of contrapuntal and fugal techniques are displayed.
In Bach’s lifetime, he was able to exhibit most of the different musical structures in the period, except opera, this made his works into examples and references that influenced other composers. Few other composers have been to do what he did, encompassing such a wide range of musical genres, incorporating different foreign influences to create almost entirely new forms that are unique to the Baroque period. By composing such a large number of works, ranging from fugues for keyboards to concertos for orchestra, from oratorios for choirs and masses for the masses, he was able to bring the Baroque period to its greatest. The year of his death was considered by many musicologists to be the end of the Baroque period; this signifies how influential Bach has been on the musical style of that era.