Legend has it that a down- on- his- luck French nobleman created the first oxtail ragout somewhere between the years of 1789 and 1799. This was the time of the French Revolution where many upper class privileges were taken away. He begged some beef tails from the local tannery which regarded them as worthless. The soup he cooked evolved over time and eventually became a delicacy in Parisian restaurants.
By the 1800s, the soup had migrated to England, where it became an English specialty, both in its creamed and clear styles (recipe here). It is served all over Europe in fine restaurants and for special events such as anniversaries or state dinners.
Most people do not make oxtail soup from scratch, but the time it takes to produce it yields more flavor than your everyday soup. You can buy prepared stock but if you are interested in continental cooking and its history, try making it at least once for the experience.
Here, you see one part of the equation, the oxtail bones which will be browned or roasted in the first step to make stock.