U.S. Treasuries' prices changed little on Monday, with trading in the safe-haven asset class unaffected by political upheaval in Ukraine and mixed readings from big economies such as those of Germany and China.

Investors had scant guidance for trading and will likely wait until at least Thursday, when Federal Reserve chief Janet Yellen appears before Congress, according to DRW Trading strategist Lou Brien in Chicago.

"We seem to be in a time when we are floating around with the flows," Brien said. "We have Yellen on Thursday and her testimony may be a little different ... and we have some interesting data on Friday."

Data due on Friday includes the pending homes sales index for January from the National Association of Realtors. A key indicator of the important U.S. real estate sector, the index was off 8.7 percent in December. A Reuters poll signals a 2 percent month-over-month rise for January.

Markets have mostly shrugged off weaker-than-expected U.S. economic reports because much of the nation was hit by rough winter weather that had slowed business and spending, according to TD Securities analyst Gennadiy Goldberg in New York.

"We largely expect this week's key data releases to be relatively soft," Goldberg said in a commentary. "We nevertheless look for markets to discount a large portion of the data weakness due to ongoing winter weather distortions."

Investors may be stung by likely downward revisions on Friday to fourth-quarter gross domestic product estimates, said Goldberg, who sees Treasury yields grinding higher in coming weeks.

In muted New York trading, benchmark 10-year U.S. Treasury notes were off 2/32 in price, pushing the yield to 2.742 percent. The thirty-year bond was down 1/32 of a point in price, taking the yield to 3.693 percent.

Ahead of the New York open, Treasuries showed little reaction to an unexpected turn-up in German business morale, a report indicating credit tightening in China was slowing growth of home values, and the ouster in the Ukraine of President Viktor Yanukovich.

"There's uncertainty but there's uncertainty about the uncertainty," Brien said.