The Origin(s) of Knitting...

The origin(s) of knitting is greatly disputed even today. It is widely believed to have developed in Pre-Christian time, the oldest artifact appearing to be a type of sock.  Socks and stockings were the first pieces created through similar knitting techniques used today. 

The preceding technique is known as Nalebinding. Through this process, fabrics were created by the assembly of multiple knots or loops with the use of a single needle (rather than two) and thread. Here's a photo from a website I found having fairly good illustrations of the technique: Nalebinding. Here's a photo of what a nalebinding piece looks like: Nalebinding piece. 

Initial references to true knitting stemmed from Europe and dated from early 14th century. The first knitted socks, however, were from Egypt and were a bit older (11th century). The purl stitch had not yet been formatted and in order for the stockinette pattern to be produced the crafter had to knit in a circle and then cut the piece open. This process was known as "Steeking".

Reference to the purl stitch is said to have not appeared until late in the 16th century but may have still been developed a little earlier.