How should I explain this sentence:

[bttg]

I have no clear idea about the following sentence: " There are some dozen small concerns which left the States for this business that have abondoned it altogether." , particularly in the part of which and that subclause. One explanation is that some small enterprises went out of the business and handed it over to the government, and they have given it up without room for regret. Is it right?

[Ann1977]

"There are some dozen small concerns
12 small companies

which left the States
left the States (the United States?)

for this business
for what business?
How do you "leave the States for a business?"

that have abondoned it altogether."
"that" seems to refer to the 12 small companies
Have abandoned WHAT?


One explanation is that some small enterprises went out of the business
Yes, it seems that 12 small companies went out of business

and handed it
Handed their companies? Handed themselves?

over to the government,
At least in the United States, you can't hand your business over to the government. The government in the US does not operate businesses because it will not compete with private enterprise.
A failed company may have its assets SEIZED by the government to pay for back taxes, but if that happens, the government sells the assets and keeps the money.

and they have given it up
"they" refers to the 12 small companies?
"it" refers to their business?

without room for regret.
I don't see anything in the sentence about regret or any other feeling.

That sentence does not communicate anything.
No wonder you don't have a clear idea about its meaning -- there isn't any.

[bttg]

"There are some dozen small concerns
12 small companies

which left the States
left the States (the United States?)

for this business
for what business?
How do you "leave the States for a business?"

that have abondoned it altogether."
"that" seems to refer to the 12 small companies
Have abandoned WHAT?


One explanation is that some small enterprises went out of the business
Yes, it seems that 12 small companies went out of business

and handed it
Handed their companies? Handed themselves?

over to the government,
At least in the United States, you can't hand your business over to the government. The government in the US does not operate businesses because it will not compete with private enterprise.
A failed company may have its assets SEIZED by the government to pay for back taxes, but if that happens, the government sells the assets and keeps the money.

and they have given it up
"they" refers to the 12 small companies?
"it" refers to their business?

without room for regret.
I don't see anything in the sentence about regret or any other feeling.

That sentence does not communicate anything.
No wonder you don't have a clear idea about its meaning -- there isn't any.

Thanks very much anyway. Maybe only the single sentence is easy to make confused. Let me give the context as following:
"GEORGE MAY TO JOSEPH CURTISS
- We are too late
20 November 1849
You will have rec'd my last informing you of my arrival before this reaches. I regret to say tat the prospect of doing anything at our comtemplated [plan] is forbidding, that both Randall and myself judge it not best to make a trial at it. First we are too late- the time for commencing the coining business is past. There are already four establishments of this kind in California now, only two of which are doing a profitable business. One is Moffitt & Co., the other the Miners Bank, both of them (particularly the latter) with large capital. Had we arrived at the time contemplated we might perhaps have succeeded, but it is certainly too late now.
There are some dozen small concerns which left the States for this business that have abandoned it altogether. All the large merchantile and other business houses from motives of interest use their influence against it. it is more for their interest to buy the dust and send to the States than give circulation to coin made here. Unless therefore it be done by a league with some of these large establishments (which we cannot make) it is difficult to get much $20,000 has recently arrived from New England. He is [a] personal and intimate friend of mine and tells me it is quite doubtful if they attempt it all. Moffit & Co. and the Miners Bank the gamblers, who circulate more money here than any other class of men. The latter is a heavy concern owning a large amt of real estate and which redeems its coin with government coin when called upon to do so."

[Ann1977]

Yes, I see.

"Leaving the States" in 1849 means that some companies packed themselves up and traveled West by wagon train across the prairie to reach California (?) (Alaska?).

They "left the States" -- meaning they left the part of the continent that was made up of States in the Union, and headed for the "territories" - land that had not yet been granted statehood.

So the sentence as a whole means:
In the recent past, about 12 fellows tried to start businesses like this out here. They packed up everything they owned and traveled across the continent, passing out of the jurisdiction of the United States, and came all the way out here. But in the end, all those businesses failed. Their owners had to give them up, abandon them, just walk away and leave the office furniture behind, or just give up trying to make a profit from them.

There may indeed have been plenty of regret, especially if they lost a lot of money, or had to slink back home as failures.

[bttg]

Your explanation is very excellent and it enlarges my vision, thank you very much.

But there is still a question: according to you, the that clause modifies the word "concerns", despite the which clause between them also qualifies the same thing. As a beginner of English learning, I don't know whether the situation is rare or not? How can I judge which part of a sentence a clause modifies?