Song Dynasty Po Dao
The weapon known as Po Dao first appeared during the Song Dynasty. At the time it was also known as Bō Dao (撥刀), Bó Dao (博刀 or 膊刀), Zhao Ku Dao (着袴刀) and many other names. The novel Shui Hu Zhuan (《水滸傳》, varyingly translated as Water Margin, Outlaws of the Marsh, All Men Are Brothers, etc.), which was published during the Ming Dynasty but incorporated many Song and Yuan period folk stories and plays, described Po Dao as a kind of short, single-edged sword or sabre that can be quickly fixed to a wooden shaft and turned into a pole weapon.
As with other cold weapons found in Wu Bei Yao Lue, this Po Dao is special modification created by Cheng Zi Yi (程子頤). The standard design used during Ming period might be closer to modern definition of Po Dao (see below).
Qing Dynasty Pu Dao
|Drawing of a Qing Dynasty Pu Dao, from 'Qin Ding Da Qing Hui Dian Tu (《欽定大清會典圖》)'.|
Qing Dynasty introduced yet another type of Pu Dao (撲刀, note the difference between '撲' and '朴'). It is a simple, one-handed falchion issued to Lu Ying (綠營, Green Standard Army).
Late Qing Dynasty to Modern Po Dao
|Chinese soldiers during the Second Sino-Japanese War, armed with Shuang Shou Dai.|
Modern martial arts communities categorise Shuang Shou Dai, Zhan Ma Dao (斬馬刀) and Po Dao based on the length of the handle/shaft. A Shuang Shou Dai has the shortest handle (but still longer than a two-handed sword) while a Po Dao has the longest shaft, with Zhan Ma Dao lies somewhere in between. These terms are not set in stone and can be used interchangeably to some extend.
The term Yue Fei Dao (presumably 岳飛刀) is often used to describe a Shuang Shou Dai. However, this term is a modern (not to mention completely inaccurate) neologism.