What order do triggered abilities happen in if multiple things trigger at the same time?
When multiple abilities trigger at the same time (as Path and Triumph did, in this situation) and you control both of them, you can choose to put them on the stack in any order you like.


  603.3b If multiple abilities have triggered since the last time a player received priority, each player, in APNAP order, puts triggered
  abilities he or she controls on the stack in any order he or she
  chooses. (See rule 101.4.) Then the game once again checks for and
  resolves state-based actions until none are performed, then abilities
  that triggered during this process go on the stack. This process
  repeats until no new state-based actions are performed and no
  abilities trigger. Then the appropriate player gets priority.


Both Descendants&#39; Path and Triumph of Ferocity trigger at the same time, at the beginning of your upkeep. Because you control both triggers, you have a choice of how to put those two triggers on the stack, meaning you can draw a card from Triumph of Ferocity first (put Triumph's trigger on the stack on top of Path's) or reveal the card for Descendants' Path first (put Path's trigger on the stack on top of Triumph's).

Afterward, when you proceed to the draw step, you get your normal draw.

So, your actions were perfectly game-legal. But you could have changed the order and that would be correct as well.

Note that you are not drawing three cards in this situation. Descendants' Path tells you to "reveal" a card and do something with it. This does not count as "drawing" it for abilities that reference that.



For reference, "APNAP order" just means that, if both players have to do something, the player whose turn it is makes the decisions first:


  101.4. If multiple players would make choices and/or take actions at the same time, the active player (the player whose turn it is) makes
  any choices required, then the next player in turn order (usually the
  player seated to the active player’s left) makes any choices required,
  followed by the remaining nonactive players in turn order. Then the
  actions happen simultaneously. This rule is often referred to as the
  “Active Player, Nonactive Player (APNAP) order” rule.