How did the Galactic Republic defend itself before it had a clone army?

Question

This question about whether clone armies existed prior to the Clone Wars made me wonder if the Galactic Republic in the Star Wars galaxy have any military forces before the Clone Wars. That question is specifically about clone armies by anyone, while mine is about any military force specifically for defending the Republic.

We know its laws did not prevail in Outer Rim systems during the prequel trilogy. Long ago, two separate Sith empires (original and resurgent empires) from the Outer Rim attacked the Republic. The fact that the Republic did not control the entire galaxy and that empires arose multiple times from outside its control should have prompted it to create a defense force. If not, how did it enforce its borders?

The meteoric rise of the Confederacy of Independent Systems showed how vulnerable the Republic was to attack from without and dissension from within. Corporations such as the Trade Federation had their own militaries which they used to flout Republic law. They probably would not be so bold if the Republic had a military or police force to enforce its laws. During the Clone Wars, these corporations sided with the CIS and turned their droid armies against the Republic.

How would the Republic defend itself against rebellions (such as from the CIS) or invasions (such as from Sith empires)?

Answers from EU, Legends, G-canon, or D-canon are acceptable.

Answer 1

In Legends, the Republic maintains the Judicial Forces, which was in theory a civilian law enforcement agency, but it still had a substantial fleet. The famous Katana fleet was a Judicial Forces project, and many officers who would go on to serve the Imperial Navy, such as Gilad Pellaeon, served initially in the Judicial Forces.

Although the Judicial Forces were considered part of the judiciary, as the name implies, they were capable of fighting against organized threats such as during the Stark Hyperspace War (featured in the eponymous arc of the Star Wars: Republic comic).

In addition, each planet was allowed to maintain a Planetary Security Force, at its own discretion (and expense, so the quality of the PSFs varied across the Republic). These forces were mainly responsible for protecting their own worlds and colonies, plus major trade routes, while the Judicial Forces would serve as a rapid-response team in response to crises along with handling miscellaneous frontier duties. The troops and ships defending Naboo were an example of these forces.

Incidentally, the Judicial Forces were not deployed against the Trade Federation because they hadn't yet been convicted of any crimes and there was no Senate finding authorizing an intervention, because the Senate and courts were notoriously corrupt and inefficient. If such a ruling or finding had been made, the Judicial Forces would've been expected to enforce it.

Answer 2

Well, the Republic may not have had a large army, but neither did their opponents.

You see the only major enemy faction that posed a risk to the Republic was the Separatists, and when they showed up, then they got a giant army.

But before then, the Republic would still have had some form of ground troops, each individual planet in the Republic had its own army of sorts, take, for example, Naboo, they had their own troops to use to fight against the Trade Federation.

Not only that, but they had the Jedi, the Jedi are what fought against the Sith, they were probably the only defense against the Sith the Republic had. They would also keep the peace even after the Sith were "gone". So any minor rebellions could be quashed by the Jedi.