1. During the 16th  century instrumental music is to a large degree descended from vocal forms such as the Motet and Chanson (France).
2. The early dance forms, often paired (1.duple-slow, 2. Triple-fast) evolved finally into the 17th century Dance Suite and without doubt affected the development of instrumental music.
3. Organists were also highly important in this new development as their required skills of embellishment and transcription, regarding the Chansons particularly, legitimized instrumental music in the church.  
4. The Italian equivalent of Chanson is the Canzone.   The Gabrieli's ( Andrea 16th century, and Giovanni born mid 16th c and died in early 17th century) were organist composers at St.Mark's Basilica in Venice and Andrea, though he wrote many embellished Canzoni also wrote the first original  instrumental Canzones. The Canzoni of the 16th century were of three types or performance styles:  Florid (merely ornamented), Imitative (almost indistinguishable from the imitative Ricercar from which the Fugue is considered to have developed) and the Sectional Canzoni.
5. It is the sectional Canzones, consisting of many short sections in contrasting duple and triple meter, that have the most importance in the development of the later Baroque Trio Sonata and Solo Sonata.

The Venetian School and the Florentine Camerata

1. Giovanni Gabrieli (1557-1612) is the most distinguished composer of this 'school'  at the Basilca of St.Mark's counting among it's long line of famous organist/composers Adrian Willaert, Cipriano de Rore, Claudio Merulo, and Giovanni's uncle,  Andrea.
2. The Venetian School is credited with the first general use of the antiphonal principle in western Europe (alternating choirs and organs, and instruments).
3. The sectional canzoni  being composed by Andrea and Giovanni were difficult to unify because of the tradition (of the earlier chansons) of high contrast brought about by changes of meter . 
4. Unification was attempted by expanding each individual section to greater lengths. Finally, it seems, the size of the sections became such that the canzone split into a number of separate movements of contrasting style, tempo and meter. This is a tantalizing  development as it possibly indicates the provenance of multi-movement  instrumental works (i.e. Sonata, etc.).
5. Also, in the late 16th century at nearby Florence, the Florentine Camerata were championing a new style of writing called monody - (you should know what this group of artists were attempting and what they achieved though we will not dwell on it class) .
6. The principle of monody is the idea that the function of music is to carry the text. (I know, this is an instrumental inquiry, just hang). For our purposes we may read 'text' as 'melody' and 'music' as the nascent basso continuo. This produced a non-imitative style - most importantly a new type of melody not dependent on other contrapuntal neighbors to complete it's meaning. It was a self-contained melody and was composed  in phrase or period structure of four or eight bars. Because the 'basso continuo' allowed so much freedom in the way of added notes (read chromatic alterations) in the melody, and basically supplied a chordal accompaniment indicated by a figured bass,  the modal system was weakened and the way paved for the tonal system. From this it may also be surmised that the idea of  a composition for keyboard and melodic solo or obligato instrument was attractive.
7. The first composition that conforms to our definition of chamber music is in this Monodic style and is designed for instruments alone, not for instruments and/or voices, and its title is Canzone francese a quattro, a riposta (with repeats) and was written 1602 by Lodovico da Viadana.

From Canzone to Sonata da Chiesa

1. Before 1610 the Canzone was undergoing external and internal stylistic changes.  Giovanni Gabrieli 's compositions which used more than four voices and those that used less than four voices. 
2. The 'less than four voice' compositions gradually evolved into a more solo line or duo line with continuo about 1610 - so that at this time we can begin to find and speak of 'Sonata' and 'Sonata Style'.
3. Early sonatas by such composers as Giovanni Gabrieli (1557-1612),  Girolamo Frescobaldi (1583-1643), and Salomone Rossi (1587-1628) are characterized by a variety of features:
                     a.  variations introduced
                     b.  homophonic texture frequent
                     c.  often for 3 instruments, with upper two voices in parallel thirds
                     d.  still a 'responsive' style alla Canzone  but not in large masses of sound
                     e.  broken chord figuration for strings (which is idiomatic writing for strings)
                      f.  usually one movement multi-sectional works ( as many as ten)
                      g.  by 1625, sections are fewer and there are definite closing cadences                                         
                      h.  the result was a compound fourm consisting  3 to 5 movements in
                          contrasting tempo,  meter and style.
4. Eventually, in the 17th century with Marco Uccellini (1605-80) we can find separate movements rather than sections. His sonata violin sonata Op. 5 with basso continuo (1649) is monothematic in its structure and he depends upon sequence repetition in fairly long phrases. From this point in this type of sonata reference will be made entirely to 'movements'.