The Makedonian phalanx -- why such depth?

[Paralus]

The slangy-minded Greeks and Macedonians were as fond of nicknames as we are.......and in that case sarissa might not be a specific weapon (infantry pike 18-24 ft long), with the name mis-applied as a nickname, but instead, as Paralus has suggested, be a more generic 'extra-long spear' and thus anything longer than a 'dory'......except that a 12 ft cavalry spear had a specific name - 'xyston' !

Accordingly, I think 'sarissaphoroi' was just a loose use of the term as a nickname for the 'xyston' armed 'mounted scouts' ('prodromoi')

It is possible that the 'sarissa' was of Thracian origin, and adopted by Philip from them......

Whilst nothing is ever certain, that last is a distinct possibility. Thracians are described as utilising 12’ (if I recall correctly) spears. The Macedonians (especially those immediately pre-dating Philip II) will have had memories of these much like the Romans and their fears of barbarian invasion one imagines.

Further, I don’t believe, as Markle argues, that the Macedonian cavalry – sarissphoroi, prodromoi or the Companions – carried the equivalent of the infantry sarissa into battle. I’d suggest that this was near enough to the Thracian 12’ spear that Alexander seems to be wielding in the eponymus mosaic.

To take up Paullus’/ Paul’s term “slangy-minded” and to again borrow from Agesiaos: “That ain’t no xyston, it’s a bloody sarissa!”

The term likely fell into common usage as did, possibly, aestheairoi. Arrian qualifies it as “so called” Aesthetairoi possibly indicating a nickname of sorts originally.