MaximumPC provides a brief history of x86 processor, you can check it out over here. It all started 31 years ago with the launch of the Intel 8086 processor:
In the beginning, Intel created the 8086 and its first 16-bit microprocessor.
And Intel said, Let there be x86: and there was x86.
And Intel saw the x86, that it was good.
No, we're not about to anoint Intel as a deity, but the gargantuan chip maker did give birth to the x86 processor. More than 30 years later, or roughly 3,000 calendar years in computer time, x86 continues to evolve (see how easy it is for creationism and evolution to co-exist?) from its modest start in 1978. That was the year Intel created the 8086, a 3-micron chip chugging along at 4.77MHz, while later versions would run at up to 10MHz. The 8086 had just 29,000 transistors, which was still nearly four times as many as the 8085 released in 1976, and was Intel's first 16-bit microprocessor and responsible for kicking off the 16-bit era (note that the 8086 wasn't the first 16-bit chip). Backwards compatibility with software written for the 8008, 8080, and 8085, and the ability to address 1MB of memory natively made the 8086 a near instant success.